416 results on '"non-parametric methods"'
Search Results
2. Technical efficiency in banks: a review of methods, recent innovations and future research agenda.
- Author
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Akdeniz, Özlem O., Abdou, Hussein A., Hayek, Ali I., Nwachukwu, Jacinta C., Elamer, Ahmed A., and Pyke, Chris
- Abstract
Technical efficiency in banking is a critical aspect of the financial industry and has been widely studied using various measurement techniques. This systematic literature review offers a comprehensive examination of 305 studies on the application of technical efficiency measurement techniques in both Islamic and conventional banking sectors from 1989 to 2019. Our comprehensive analysis not only provides a broad view of the efficiency measurement literature but also outlines a future research agenda. Despite the extensive research in this field, several issues remain unresolved, including input–output selection, a comparison of efficiency between Islamic and conventional banks, limited cross-country studies, and a lack of exploration into the impact of regulation and Shariah principles. To address these gaps, this review highlights the most commonly used methods, variables, and findings and provides three key recommendations for future research. Three key themes emerge from our examination. First, there is a need to better understand and the application of new frontier techniques other than the traditional methods, which currently dominate the existing literature. Second, the intermediation approach is the most frequently used in variable selection, thus more studies with comparative findings with applications of production and value-added approaches are suggested. Third, the most frequently used input variables are 'labor', 'deposits' and 'capital', whilst 'loans' and 'other earning assets' are the most popular output variables. We recommend three vital directions for future research: (i) non-interest expenses to be included amongst the inputs, while non-interest income should be added to the list of outputs, especially when estimating efficiency scores of Islamic banks. (ii) The impact of environmental variables such as, inter alia, Shariah principles, country-specific factors, and management quality is suggested to be considered simultaneously in models measuring and comparing the efficiency of Islamic and conventional banks. (iii) The selection of performance metrics employed should be expanded to include both the standard efficiency scores and the Malmquist Total Factor Productivity Index (TFP). The paper concludes with research needs and suggests directions for future research. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. تجزیه پایداری عملکرد دانه لاینهای اینبرد نوترکیب گندم نان.
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محسن سبزی نوجه ده, سعید اهری زاد, and مینا امانی
- Subjects
SUSTAINABILITY ,GRAIN yields ,PLANT yields ,BLOCK designs ,GENOTYPES - Abstract
Background & Objective: Investigating the stability and compatibility of a genotype in different environmental conditions in order to introduce it for planting in specific and known environmental conditions in multi-breeding programs is one of the basic needs and to achieve sustainable production in order to achieve sustainable self-sufficiency in It is necessary to produce strategic products, especially wheat. Methods & Materials: In the present study, in order to investigate the stability and identify high-yielding and compatible genotypes, the yield of 32 lines of recombinant inbred from the crossing of two cultivars Roshan and Superhead in the form of a randomized complete block design with three replications in six The region (Tabriz, Ahar, Ardabil, Faghan, Shabestar and Urmia) were investigated for two years. Results: The results of the present study showed that there was a significant difference between the locations in terms of performance. Also, the difference between genotypes, as well as the interaction effect of genotype × year, genotype × location, and the interaction effect of genotype × year × location were significant, which indicated the difference between the performance of genotypes in different environments, which indicated the necessity of stability analysis. Conclusion: The results of analysis of simple and compound variances showed a significant difference between the lines in terms of grain yield. Comparing the average of all the lines, lines No. 3, 12, 38, 42, 47, 95 and Roshan had the highest yield and the lowest average seed yield was related to line 51 with 3.023 tons per hectare. Line 90 showed good general compatibility compared to other lines. Lines No. 3, 38, 42, 95, their regression coefficient was less than one and the deviation from their regression line was higher. One of the practical aspects of this research is the identification of promising lines for carrying out further breeding studies in order to release the variety and introduce it to farmers. According to the relative alignment of the results obtained from different methods, it can be stated that in this research, lines 10, 12, 31 and the Roshan variety were recognized as the most stable genotypes and line 51 as the most unstable line and It was recognized as special for unfavorable areas. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Violence as a Legacy: Impact of Witnessing Parental Violence
- Author
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Kothari, Richa, Husain, Zakir, Dutta, Mousumi, Kothari, Richa, Husain, Zakir, and Dutta, Mousumi
- Published
- 2024
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- View/download PDF
5. Review on Statistical Post-processing of Ensemble Forecasts
- Author
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Yadav, Rashmi, Yadav, Sanjaykumar M., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Patel, Dhruvesh, editor, Kim, Byungmin, editor, and Han, Dawei, editor
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- 2024
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6. Investigating the Impacts of Climate and Land Use Change on the Hydrologic Characteristics in the Sub-Basins of the Dez River, Middle East
- Author
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Zohreh Khorsandi Kouhanestani
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climate change ,discharge ,land use ,non-parametric methods ,structural equation model ,Water supply for domestic and industrial purposes ,TD201-500 - Abstract
Human activities and the climate change affects the river flow therefore monitoring flow rate of river for an extended period can reveal the detail of involved mechanisms in these changes. The previous studies show impact of human activities and climate change on river temporal variations varies in different locations. Water scarce is one of most problem in this area therefore finding affected parameters in water accessibility is important for water management in Middle East. This study aimed to investigate the trend of annual and monthly flow changes in the Dez River branches in southwestern Iran by several nonparametric methods. A structural equation model was used to assess the effects of land use and climate changes on river discharge. The study results showed that the annual precipitation at all stations has no significant trend, but temperature and evaporation at most stations increased significantly. Additionally, more than 30% of the study area's rangeland and forestlands have been converted into agricultural and residential lands. The results showed that land use and climate can determine 43.2% of discharge changes. Also, land use changes are more effective than climate change on river discharge changes.
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- 2024
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7. Painful differences between different pain scale assessments: The outcome of assessed pain is a matter of the choices of scale and statistics
- Author
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Svensson Elisabeth and Lund Iréne
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comparability ,ordered categorical data ,non-parametric methods ,numeric rating scale ,pain scales ,paired data ,rank-invariance ,relationship ,verbal descriptive scale ,visual analogue scale ,Special situations and conditions ,RC952-1245 ,Medicine (General) ,R5-920 - Abstract
Perceived pain is a multi-factorial subjective variable, commonly measured by numeric rating scales, verbal descriptive scales (VDS), or by a position on an analogue line (VAS). A major question is whether an individual’s VAS and VDS pain assessments, on the same occasion, could be comparable. The aim was to compare continuous and discretized VAS pain data with verbal descriptive pain datasets from the Oswestry Disability Index (ODI) and the European Quality of Life Scale (EQ-5D) in paired pain datasets.
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- 2024
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8. Ongoing Multivariate Chemometric Approaches in Bioactive Compounds and Functional Properties of Foods—A Systematic Review.
- Author
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Karadžić Banjac, Milica, Kovačević, Strahinja, and Podunavac-Kuzmanović, Sanja
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FUNCTIONAL foods ,CHEMOMETRICS ,BIOACTIVE compounds ,FOOD science - Abstract
In this review, papers published in the chemometrics field were selected in order to gather information and conduct a systematic review regarding food science and technology; more precisely, regarding the domain of bioactive compounds and the functional properties of foods. More than 50 papers covering different food samples, experimental techniques and chemometric techniques were selected and presented, focusing on the chemometric methods used and their outcomes. This study is one way to approach an overview of the current publications related to this subject matter. The application of the multivariate chemometrics approach to the study of bioactive compounds and the functional properties of foods can open up even more in coming years, since it is fast-growing and highly competitive research area. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Trend Analysis and Change Points in Time Series of Water Level of Shallow and Deep Wells in Gorganrood Watershed
- Author
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T. Mohammadi, V. Sheikh, A. Zare, and M. Salarijazi
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groundwater level ,water table drawdown ,non-parametric methods ,gorgan plain ,Agriculture ,Agriculture (General) ,S1-972 - Abstract
A quantitative study of groundwater resources and accurate monitoring of changes over time, especially in areas facing limited water resources, is considered essential for proper management and sustainable exploitation of these resources. Golestan province, one of the semi-arid provinces of Iran has faced a drop in the groundwater level and an increase in the salinity of the groundwater due to the excessive withdrawals from the groundwater table and the reduction of atmospheric precipitation in the past few years. Gorgan Plain with an area of about 4727 square kilometers is one of the largest plains in Iran and the most important plain of Golestan province in terms of water supply for agricultural and drinking purposes. In this plain, there is a network of piezometers and observation wells that include continuous monthly measurements for more than 30 years. The objective of this research was to investigate the changes in the groundwater level of shallow (30 years (1989-2018)) and deep (22 years (1997-2018)) wells. The Man-Kendall method was used to reveal the trend and Pettitt, Normal Standard, and Buishand methods were used to identify sudden change points in a time series of groundwater levels in 49 shallow wells and 12 deep wells. The results of this research showed that the groundwater level in most of the studied wells had a significantly decreasing trend at a significant level of 5%. Also, the largest amount of groundwater loss was in the southern and southwestern parts of the plain, which can be attributed to a large amount of water taken from the wells due to their proximity to urban areas and some local conditions such as the proximity of the wells of this area are located in altitudes and at the entrance border of the aquifer. In the same way, as it rises, the fall decreases in the middle of the plain, and the amount of fall decreases in the northern areas and the edge of the Caspian Sea. It can be related to the proximity to the Caspian Sea and the high water table, and as a result, the inappropriate quality of water and land (high salinity and low fertility), which has caused the water withdrawal from this area to be less.
- Published
- 2023
10. Estimation in the Presence of Heteroskedasticity of Unknown Form: A Lasso-based Approach.
- Author
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González-Coya, Emilio and Perron, Pierre
- Subjects
- *
HETEROSCEDASTICITY , *TIME series analysis , *REGRESSION analysis , *STATISTICAL sampling , *COVARIANCE matrices - Abstract
We study the Feasible Generalized Least-Squares (FGLS) estimation of the parameters of a linear regression model in the presence of heteroskedasticity of unknown form in the errors. We suggest a Lasso based procedure to estimate the skedastic function of the residuals. The advantage of using Lasso is that it can handle a large number of potential covariates, yet still yields a parsimonious specification. Using extensive simulation experiments, we show that our suggested procedure always provide some improvements in the precision of the parameter of interest (lower Mean-Squared Errors) when heteroskedasticity is present and is equivalent to OLS when there is none. It also performs better than previously suggested procedures. Since the fitted value of the skedastic function falls short of the true specification, we form confidence intervals using a bias-corrected version of the usual heteroskedasticity-robust covariance matrix estimator. These have the correct size and substantially shorter length than when using OLS. Our method is applicable to both cross-section (with a random sample) and time series models, though here we concentrate on the former. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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11. CONTRASTE O PRUEBA DE HIPÓTESIS E INTRODUCCIÓN AL ANÁLISIS DE REGRESIÓN LINEAL O AJUSTE DE MÍNIMOS CUADRADOS. NOTAS PARA DOCTORANDOS.
- Author
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ROCA-FERNÁNDEZ, C. and MULLOR, M.
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STATISTICAL hypothesis testing ,REGRESSION analysis ,LINEAR statistical models ,INFERENTIAL statistics ,UNIVERSITY research - Abstract
Copyright of Revista de Ingenieria, Matematicas y Ciencias de la Informacion is the property of Corporacion Universitaria Republicana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
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12. Exploring Agricultural Disparities in Western Odisha: A Comprehensive Study Based on Composite Index Scores.
- Author
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MUNDA, SURU, GARTIA, RAJENDRA, and DASH, SAMIR RANJAN
- Subjects
AGRICULTURAL productivity ,CROP yields ,AGRICULTURAL development ,STATISTICAL sampling - Abstract
The research endeavor delves into the intricate agricultural disparities prevalent in Western Odisha, focusing on crucial metrics such as land area, yield rates, and production trends spanning the years 2020 to 2022. The study encompassed an extensive scope, encompassing 50 blocks distributed across six carefully selected districts: Nuapada, Jharsuguda, Boudh, Sundargarh, Sambalpur, and Baragarh. These districts were meticulously chosen through a process of simple random sampling from a pool of ten districts in the Western Odisha region. To distill meaningful insights, the research harnessed the power of composite indices, drawn from a comprehensive set of fifteen indicators, each illuminating distinct facets of agricultural development. Through the application of Principal Component Analysis (PCA), five key indicators were expertly extracted from this data set. Drawing upon secondary data sourced from the esteemed Statistical Abstracts of Western Odisha districts, and the Directorate of Economics and Statistics (DES), Government of Odisha (2019-2020), the study validated its assumptions by subjecting the extracted components to the rigors of the Kolmogorov-Smirnov test for normal distribution. Primary data was diligently collected from a cohort of 300 households via meticulously structured questionnaires, encompassing vital parameters such as land area (measured in acres), yield rates (measured in kilograms), and production figures (measured in quintals). It was discovered that the data exhibited deviations from normality, prompting the application of non-parametric methodologies. The ensuing Kruskal-Wallis tests unearthed significant disparities among the identified groups, emphasizing substantial distinctions between the Meteoric, Progressive, Mediocre, and Laggard classifications. To gauge the extent of these disparities, the Gini Coefficient (GC) was aptly employed. The findings underscored that the Meteoric group exhibited more pronounced disparities in land area compared to the other groups, along with marked differences in yield rates. Additionally, this group displayed slightly elevated disparities in production figures. These revelatory results furnish a nuanced understanding of the diverse variances in land area, yield rates, and production levels among the distinct groups. This research endeavor, by shedding light on the dynamic agricultural landscape of Western Odisha, not only highlights the disparities but also offers valuable insights into the underlying factors influencing these agricultural outcomes. These insights, in turn, pave the way for targeted interventions aimed at augmenting agricultural productivity in the region. Addressing these identified disparities emerges as a critical step towards fostering a more equitable and sustainable agricultural sector in Western Odisha. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. Impact of combination methods on extreme precipitation projections.
- Author
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Jessup, Sébastien, Mailhot, Mélina, and Pigeon, Mathieu
- Subjects
PRECIPITATION (Chemistry) ,EXTREME weather ,CLIMATE change ,ACTUARIES ,QUANTILES - Abstract
Climate change is expected to increase the frequency and intensity of extreme weather events. To properly assess the increased economical risk of these events, actuaries can gain in relying on expert models/opinions from multiple different sources, which requires the use of model combination techniques. From non-parametric to Bayesian approaches, different methods rely on varying assumptions potentially leading to very different results. In this paper, we apply multiple model combination methods to an ensemble of 24 experts in a pooling approach and use the differences in outputs from the different combinations to illustrate how one can gain additional insight from using multiple methods. The densities obtained from pooling in Montreal and Quebec City highlight the significant changes in higher quantiles obtained through different combination approaches. Areal reduction factor and quantile projected changes are used to show that consistency, or lack thereof, across approaches reflects the uncertainty of combination methods. This shows how an actuary using multiple expert models should consider more than one combination method to properly assess the impact of climate change on loss distributions, seeing as a single method can lead to overconfidence in projections. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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14. Parametric and Non-Parametric Regression Methods
- Author
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Reddy, T. Agami, Henze, Gregor P., Reddy, T. Agami, and Henze, Gregor P.
- Published
- 2023
- Full Text
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15. Longitudinal data clustering methods: A Systematic Review
- Author
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Arefeh Dehghani tafti, Yunes Jahani, Sara Jambarsang, and Abbas Bahrampour
- Subjects
clustering ,longitudinal data ,non-parametric methods ,model-based methods. ,Biology (General) ,QH301-705.5 ,Probabilities. Mathematical statistics ,QA273-280 - Abstract
In the last few decades, in many research fields, different methods were introduced to discover groups with the same trends in longitudinal data. The clustering process is an unsupervised learning method, which classifies longitudinal data based on different criteria by performing algorithms. The current study was performed with the aim of reviewing various methods of longitudinal data clustering, including two general categories of non-parametric methods and model-based methods. PubMed, SCOPUS, ISI, Ovid, and Google Scholar were searched between 2000 and 2021. According to our systematic review, the non-parametric k-means Clustering Method utilizing Euclidean distance emerges as a leading approach for clustering longitudinal data This research, with an overview of the studies done in the field of clustering, can help researchers as a toolbox to choose various methods of longitudinal data clustering in idea generation and choosing the appropriate method in the classification and analysis of longitudinal data.
- Published
- 2023
- Full Text
- View/download PDF
16. تحلیل روند و نقاط تغییر در سریهای زمانی تر از آب چاه های کم عمق و عمیق حوضه آبریز گرگانرود.
- Author
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طاهره محمدی, واحد بردی شیخ, آرش زارع گاریزی, and و میثم سالاری جزی
- Subjects
- *
WATER table , *PLAINS - Abstract
A quantitative study of groundwater resources and accurate monitoring of changes over time, especially in areas facing limited water resources, is considered essential for proper management and sustainable exploitation of these resources. Golestan province, one of the semi-arid provinces of Iran has faced a drop in the groundwater level and an increase in the salinity of the groundwater due to the excessive withdrawals from the groundwater table and the reduction of atmospheric precipitation in the past few years. Gorgan Plain with an area of about 4727 square kilometers is one of the largest plains in Iran and the most important plain of Golestan province in terms of water supply for agricultural and drinking purposes. In this plain, there is a network of piezometers and observation wells that include continuous monthly measurements for more than 30 years. The objective of this research was to investigate the changes in the groundwater level of shallow (30 years (1989-2018)) and deep (22 years (1997-2018)) wells. The Man-Kendall method was used to reveal the trend and Pettitt, Normal Standard, and Buishand methods were used to identify sudden change points in a time series of groundwater levels in 49 shallow wells and 12 deep wells. The results of this research showed that the groundwater level in most of the studied wells had a significantly decreasing trend at a significant level of 5%. Also, the largest amount of groundwater loss was in the southern and southwestern parts of the plain, which can be attributed to a large amount of water taken from the wells due to their proximity to urban areas and some local conditions such as the proximity of the wells of this area are located in altitudes and at the entrance border of the aquifer. In the same way, as it rises, the fall decreases in the middle of the plain, and the amount of fall decreases in the northern areas and the edge of the Caspian Sea. It can be related to the proximity to the Caspian Sea and the high water table, and as a result, the inappropriate quality of water and land (high salinity and low fertility), which has caused the water withdrawal from this area to be less. [ABSTRACT FROM AUTHOR]
- Published
- 2023
17. Longitudinal Data Clustering Methods: A Systematic Review.
- Author
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Tafti, Arefeh Dehghani, Jahani, Yunes, Jambarsang, Sara, and Bahrampour, Abbas
- Subjects
RESEARCH ,LEARNING ,ALGORITHMS - Abstract
Introduction: In the last few decades, in many research fields, different methods were introduced to discover groups with the same trends in longitudinal data. The clustering process is an unsupervised learning method, which classifies longitudinal data based on different criteria by performing algorithms. The current study was performed with the aim of reviewing various methods of longitudinal data clustering, including two general categories of non-parametric methods and model-based methods. Methods: In this research, to obtain related scientific articles, PubMed, Science Direct Scopus, ISI, and Google Scholar were searched between 2000 and 2021. Results: According to our systematic review, the non-parametric k-means Clustering Method utilizing Euclidean distance emerges as a leading approach for clustering longitudinal data. Conclusion: This research, with an overview of the studies done in the field of clustering, can help researchers as a toolbox to choose various methods of longitudinal data clustering in idea generation and choosing the appropriate method in the classification and analysis of longitudinal data. [ABSTRACT FROM AUTHOR]
- Published
- 2023
18. Data analysis -- preference of pertinent statistical method in research.
- Author
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Teli, Anita, Nayaka, Rekha, and Ghatanatti, Ravi
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COHEN'S kappa coefficient (Statistics) ,FISHER exact test ,DATA analysis ,STATISTICAL measurement ,RESEARCH methodology - Abstract
This article provides a comprehensive overview of the importance of selecting the right statistical method for data analysis in biomedical research. It explains the differences between parametric and non-parametric methods and highlights the need to consider the purpose of the study, the type of data, and the measurements when choosing a statistical test. The article offers a range of parametric and non-parametric approaches for comparing means, proportions, and other statistical techniques. It also discusses the benefits and drawbacks of non-parametric methods, emphasizing their usefulness when data does not meet the assumptions of parametric tests. The article stresses the significance of sample size and the p-value in determining statistical significance and concludes by emphasizing the importance of researchers having a basic understanding of statistics to select the appropriate statistical methods for their research. [Extracted from the article]
- Published
- 2023
- Full Text
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19. An epistatic interaction between pre-natal smoke exposure and socioeconomic status has a significant impact on bronchodilator drug response in African American youth with asthma
- Author
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Magaña, J, Contreras, MG, Keys, KL, Risse-Adams, O, Goddard, PC, Zeiger, AM, Mak, ACY, Elhawary, JR, Samedy-Bates, LA, Lee, E, Thakur, N, Hu, D, Eng, C, Salazar, S, Huntsman, S, Hu, T, Burchard, EG, and White, MJ
- Subjects
Data Management and Data Science ,Information and Computing Sciences ,Biological Sciences ,Bioinformatics and Computational Biology ,Social Determinants of Health ,Lung ,Pediatric ,Health Disparities ,Asthma ,Minority Health ,2.1 Biological and endogenous factors ,Respiratory ,Good Health and Well Being ,Epistatic interactions ,Non-parametric methods ,Asthma drug response ,Health disparities ,Pediatric asthma ,Epistatic interactions ,Non-parametric methods ,Asthma drug response ,Health disparities ,Pediatric asthma ,Artificial Intelligence and Image Processing ,Medical Biochemistry and Metabolomics ,Specialist Studies in Education ,Bioinformatics and computational biology ,Data management and data science - Abstract
BackgroundAsthma is one of the leading chronic illnesses among children in the United States. Asthma prevalence is higher among African Americans (11.2%) compared to European Americans (7.7%). Bronchodilator medications are part of the first-line therapy, and the rescue medication, for acute asthma symptoms. Bronchodilator drug response (BDR) varies substantially among different racial/ethnic groups. Asthma prevalence in African Americans is only 3.5% higher than that of European Americans, however, asthma mortality among African Americans is four times that of European Americans; variation in BDR may play an important role in explaining this health disparity. To improve our understanding of disparate health outcomes in complex phenotypes such as BDR, it is important to consider interactions between environmental and biological variables.ResultsWe evaluated the impact of pairwise and three-variable interactions between environmental, social, and biological variables on BDR in 233 African American youth with asthma using Visualization of Statistical Epistasis Networks (ViSEN). ViSEN is a non-parametric entropy-based approach able to quantify interaction effects using an information-theory metric known as Information Gain (IG). We performed analyses in the full dataset and in sex-stratified subsets. Our analyses identified several interaction models significantly, and suggestively, associated with BDR. The strongest interaction significantly associated with BDR was a pairwise interaction between pre-natal smoke exposure and socioeconomic status (full dataset IG: 2.78%, p = 0.001; female IG: 7.27%, p = 0.004)). Sex-stratified analyses yielded divergent results for females and males, indicating the presence of sex-specific effects.ConclusionsOur study identified novel interaction effects significantly, and suggestively, associated with BDR in African American children with asthma. Notably, we found that all of the interactions identified by ViSEN were "pure" interaction effects, in that they were not the result of strong main effects on BDR, highlighting the complexity of the network of biological and environmental factors impacting this phenotype. Several associations uncovered by ViSEN would not have been detected using regression-based methods, thus emphasizing the importance of employing statistical methods optimized to detect both additive and non-additive interaction effects when studying complex phenotypes such as BDR. The information gained in this study increases our understanding and appreciation of the complex nature of the interactions between environmental and health-related factors that influence BDR and will be invaluable to biomedical researchers designing future studies.
- Published
- 2020
20. A non-parametric approach to determine an efficient premium for drought insurance
- Author
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Manitra A. Rakotoarisoa and Harry P. Mapp
- Subjects
drought insurance ,non-parametric methods ,stochastic dominance ,africa ,Sociology (General) ,HM401-1281 ,Economic history and conditions ,HC10-1085 - Abstract
Insurance to deal with prolonged drought periods in rural Africa requires a practical method to estimate accurate premium values that minimize economic losses. We use non-parametric methods to determine the risk non-neutral insurer’s premium for drought insurance on rain-fed crops. Premium values are estimated on the basis of percentage of the expected yield losses over the potential yields. Expected yield losses are estimated based on data on the levels of rainfall, potential evapotranspiration and water-holding capacity of the soil, and water requirement of the crop. Maize crop in West Kenya, and rice crop in the Central High Plains of Madagascar are taken as case studies. To check if farmer’s choice of starting seasons affects the expected yields and the values of premium, we employ forecasted yields for two different sowing dates (October vs. November) for maize, and two different transplantation dates (November vs. December) for rice. The mean-variance (E-V), the First-Degree Stochastic Dominance (FSD), and the Second-Degree Stochastic Dominance (SSD) efficiency criteria are used to rank each pair of distributions. Results show that an insurer for maize production in Western Kenya would require a premium value between 43 and 55% of the potential yields to fully cover the loss caused by lack of rainfall. Under E-V and FSD, the two yield distributions cannot be ranked, but under SSD the yield distribution of the October-sown maize dominates that of November. For lowland rice in the Central High Plains of Madagascar, all three efficiency criteria indicate that the yield distribution of the December-transplanted rice dominates that of November and the premium values are less than 4 % of the potential yields.
- Published
- 2023
- Full Text
- View/download PDF
21. Forest Structure of Pinus ayacahuite in Southern Mexico: A Non-Parametric Analysis
- Author
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Karla Mayté Pérez-Vásquez, Wenceslao Santiago-García, Gregorio Ángeles-Pérez, Faustino Ruiz-Aquino, and Elias Santiago-García
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Pinus ayacahuite ,tree stratum ,non-parametric methods ,irregular forest stands ,Forestry ,SD1-669.5 - Abstract
Spatial structure refers to the horizontal and vertical arrangement of individual trees, and the most accurate way to describe it within a community is to characterize tree strata in terms of their dimensions. The aim of this study was to determine the horizontal and vertical structure of pure stands of Pinus ayacahuite Ehrenb. ex Schltdl., in forests of southern Mexico. Forest measurement data from 24 sample plots were used. For analysis of the horizontal structure, diameters within a range of 0.20 cm to 77 cm were used, while for the vertical structure, heights were from 0.09 m to 40.9 m. Non-parametric histograms and Kernel density methods were used in the analysis, and Fisher and Marron multimodality tests were performed. The homogeneity of the forest stands was determined by the coefficient of homogeneity, and the vertical and horizontal structures were described using the stratification proposed by Pretzsch. The results indicate that the horizontal structure corresponds to a diameter distribution with a reversed "J" shape in 79.2% of the sample plots, while 91.8% of the sites were classified as irregular with coefficients of homogeneity of 1.0 to 3.0. In the vertical structure, it was observed that the lower stratum predominated in 75% of the plots, while 25% had a higher concentration of individuals in the middle stratum. The upper stratum had accumulation percentages ranging from 1.3% to 33.3% but did not predominate in any of the plots. According to the multimodality tests, 50% of the plots present multimodality in the horizontal structure, while in the vertical structure this condition is present in 38% of the plots. Knowledge of the spatial structure of Pinus ayacahuite forest stands is essential to define silvicultural strategies that ensure the sustainable functioning of the ecosystem in terms of yield continuity and conservation.
- Published
- 2023
- Full Text
- View/download PDF
22. Beyond the mean: Distributional differences in earnings and mental health in young adulthood by childhood health histories
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Emmanuelle Arpin, Claire de Oliveira, Arjumand Siddiqi, and Audrey Laporte
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Child health ,Distributional inequalities ,Mental health/developmental disorders ,Chronic conditions ,Non-parametric methods ,Educational attainment ,Public aspects of medicine ,RA1-1270 ,Social sciences (General) ,H1-99 - Abstract
Research on the long-term effects of health in early life has predominantly relied on parametric methods to assess differences between groups of children. However, this approach leaves a wealth of distributional information untapped. The objective of this study was to assess distributional differences in earnings and mental health in young adulthood between individuals who suffered a chronic illness in childhood compared to those who did not using the non-parametric relative distributions framework. Using data from the Panel Study of Income Dynamics, we find that young adults who suffered a chronic illness in childhood fare worse in terms of earnings and mental health scores in adulthood, particularly for individuals reporting a childhood mental health/developmental disorder. Covariate decompositions suggest that chronic conditions in childhood may indirectly affect later outcomes through educational attainment: had the two groups had similar levels of educational attainment, the proportion of individuals with a report of a chronic condition in childhood in the lower decile of the relative earnings distribution would have been reduced by about 20 percentage points. Findings may inform policy aimed at mitigating longer run effects of health conditions in childhood and may generate hypotheses to be explored in parametric analyses.
- Published
- 2023
- Full Text
- View/download PDF
23. Feature Selection for Trustworthy Regression Using Higher Moments
- Author
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Hinder, Fabian, Brinkrolf, Johannes, Hammer, Barbara, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Pimenidis, Elias, editor, Angelov, Plamen, editor, Jayne, Chrisina, editor, Papaleonidas, Antonios, editor, and Aydin, Mehmet, editor
- Published
- 2022
- Full Text
- View/download PDF
24. Time-Varying Assets Clustering via Identity-Link Latent-Space Infinite Mixture: An Application on DAX Components
- Author
-
Peruzzi, Antonio, Casarin, Roberto, Corazza, Marco, editor, Perna, Cira, editor, Pizzi, Claudio, editor, and Sibillo, Marilena, editor
- Published
- 2022
- Full Text
- View/download PDF
25. Productivity of Services in the Countries of Central and Eastern Europe: Analysis Using Malmquist Indices.
- Author
-
Alcalá-Ordóñez, Alejandro, Alcalá-Olid, Francisco, and Cárdenas-García, Pablo Juan
- Subjects
INDUSTRIAL productivity ,SERVICE industries ,COUNTRIES - Abstract
This research aims to study the growth of productivity in the service sector in the former Central and Eastern European Countries (CEECs) and their determinants. For this purpose, non-parametric frontier techniques were used to measure the variations in productivity and determine the explanatory factors of these changes in total factor productivity; the methodology of the Malmquist index with output orientation and its decomposition in technical change, pure technical efficiency and scale efficiency was used for the period 2000–2019. The results obtained indicate that the productivity of services in the most recently incorporated countries grew by 1.3 per 100 on average per year compared to 1.6 per 100 in manufacturing. The most important driver of such growth was found to be improvement in technical change (frontier shift) rather than improvement in efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
26. A crop's spectral signature is worth a compressive text.
- Author
-
Cheng, Wei, Ye, Hongrui, Wen, Xiao, Su, Qi, Hu, Huanran, Zhang, Jiachen, and Zhang, Feifan
- Subjects
- *
NATURAL language processing , *IMAGE recognition (Computer vision) , *COMPRESSORS , *PIXELS , *CLASSIFICATION , *DEEP learning - Abstract
The accuracy of crop mapping based on remotely sensed hyperspectral imagery has been significantly improved through the use of deep learning. However, traditional deep learning can be computationally intensive, requiring millions of parameters, which can make it 'expensive' to deploy and optimize. Inspired by studies in natural language processing, we consider the spectral signature corresponding to each pixel as text. Specifically, we first feed the hyperspectral image (HSI) data into the Channel2Vec module to generate channel embeddings. Based on the channel embeddings, we use a lossless compressor and Normalized Compression Distance (NCD) to create a spectral tokenizer. It can segment the spectral signature corresponding to each pixel into multiple windows along the channel dimension, and then extract local sequence information from each window. By combining the local sequence information with the original HSI data, we construct spectral embeddings. Finally, we again use the lossless compressor to compute the NCD between the spectral embeddings, and then classify using only the k -nearest-neighbor classifier (k NN). The proposed framework is ready-to-use and lightweight. Without any training, it achieves results competitive with deep learning models on three benchmark datasets. It outperforms the average of 11 advanced deep learning methods trained at scale. Moreover, it outperforms more than half of these models in the few-shot scenario, where there are not enough labels to effectively train a neural network. • Introducing compressor-based classification from NLP into HSI classification. • Channel2Vec and Spectral Tokenizer are proposed for spectral representation. • The framework is ready-to-use and lightweight without any training. • The framework outperforms 11 deep learning models on average across three datasets. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. A NON-PARAMETRIC APPROACH TO DETERMINE AN EFFICIENT PREMIUM FOR DROUGHT INSURANCE.
- Author
-
Rakotoarisoa, Manitra A. and Mapp, Harry P.
- Subjects
DROUGHTS ,ECONOMIC development ,RAINFALL ,SOWING ,INSURANCE companies - Abstract
Insurance to deal with prolonged drought periods in rural Africa requires a practical method to estimate accurate premium values that minimize economic losses. We use non-parametric methods to determine the risk non-neutral insurer's premium for drought insurance on rain-fed crops. Premium values are estimated on the basis of percentage of the expected yield losses over the potential yields. Expected yield losses are estimated based on data on the levels of rainfall, potential evapotranspiration and water-holding capacity of the soil, and water requirement of the crop. Maize crop in West Kenya, and rice crop in the Central High Plains of Madagascar are taken as case studies. To check if farmer's choice of starting seasons affects the expected yields and the values of premium, we employ forecasted yields for two different sowing dates (October vs. November) for maize, and two different transplantation dates (November vs. December) for rice. The mean-variance (E-V), the First-Degree Stochastic Dominance (FSD), and the Second-Degree Stochastic Dominance (SSD) efficiency criteria are used to rank each pair of distributions. Results show that an insurer for maize production in Western Kenya would require a premium value between 43 and 55% of the potential yields to fully cover the loss caused by lack of rainfall. Under E-V and FSD, the two yield distributions cannot be ranked, but under SSD the yield distribution of the October-sown maize dominates that of November. For lowland rice in the Central High Plains of Madagascar, all three efficiency criteria indicate that the yield distribution of the December-transplanted rice dominates that of November and the premium values are less than 4 % of the potential yields. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
28. Monitoring type B buyer-supplier relationships.
- Author
-
Faraz, Alireza, Sanders, Nada, Zacharia, Zach, and Gerschberger, Markus
- Subjects
SUPPLIER relationship management ,SUPPLY chain management ,SUPPLY chains ,INFORMATION technology ,QUALITY control ,SUPPLIERS - Abstract
The ability to monitor supplier performance is a critical capability for maintaining strong buyer-supplier relationships. Monitoring type B suppliers is especially challenging as they are not as clearly defined as either type A, with strong strategic partnerships, or type C, with little partnership. This research develops a non-parametric multivariate Hoteling’s T
2 control chart to capture the in-control state of a dyadic relationship (Phase I), and show how it would be developed based on survey data of buyer-supplier relationship attributes. Modelling the satisfactory level of dyadic relationship performance is very useful for identifying when the relationship begins to move away from the desired state. We then use the designed control chart to monitor the relationship between dyads over time to determine if any unusual behaviour has occurred (Phase II) and illustrate its implementation through a case study from the auto industry. This research illustrates how supply chain managers can secure and improve their supply chain performance by monitoring and maintaining strong relationships with their partners. The proposed method extends the existing SPC tools to effectively manage Type B buyer-supplier relationships. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
29. Comparison parametric and non-parametric methods in probabilistic load flow studies for power distribution networks.
- Author
-
Abbasi, Ali Reza
- Subjects
- *
POWER distribution networks , *PROBABILITY density function , *MONTE Carlo method , *ELECTRIC vehicle charging stations , *ELECTRICAL load , *LATIN hypercube sampling - Abstract
Uncertainty assessment of distribution systems performance is an obligation because of the intermittent nature of solar and wind distributed energy resources, as well as uncertainties in power demand and charging stations of electric vehicles. Consequently, efficient tools are required for load flow analysis. Many of the existing papers assume a set of given probability density functions (PDFs) to model uncertainties and develop parametric probabilistic load flow tools. However, the uncertainties might not fall in any standard class of PDFs. As a result, non-parametric tools are required. This study compares parametric and non-parametric approaches for determining the PDFs of load flow outputs, as well as Monte Carlo simulation. To compare the methods, the unscented transform and two-point estimation approaches have been considered as parametric methods, while for non-parametric methods, saddle point approximation and kernel density estimation methods have been considered. To examine the performance of the proposed parametric and non-parametric methods, IEEE 28-bus, 33-bus, 37-bus, 69-bus and 210-bus test systems are taken into consideration and results are compared with generalized Polynomial Chaos algorithm, Latin Hypercube Sampling with Cholesky Decomposition, Cornish–Fisher expansion and clustering analysis. In terms of both accuracy and execution time, the results produced by non-parametric approaches are compared to those obtained by parametric methods. They show that the non-parametric estimators produce reliable results in estimating the density function of output random variables, while can reduce the run time for the power-flow problem in an acceptable level. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. Non-Parametric Quickest Mean-Change Detection.
- Author
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Liang, Yuchen and Veeravalli, Venugopal V.
- Subjects
- *
BETA distribution , *FALSE alarms , *PANDEMICS - Abstract
The problem of quickest detection of a change in the mean of a sequence of independent observations is studied. The pre-change observations are assumed to be stationary, while the post-change observations are allowed to be non-stationary. The case where the pre-change distribution is known is studied first, and then the extension where only the mean and variance of the pre-change distribution are known. No knowledge of the post-change distributions is assumed other than that the means of the observations are above some pre-specified threshold larger than the pre-change mean. For the case where the pre-change distribution is known, a test is derived that asymptotically minimizes the worst-case detection delay over all possible post-change distributions, as the false alarm rate goes to zero. Towards deriving this asymptotically optimal test, some new results are provided for the general problem of asymptotic minimax robust quickest change detection in non-stationary settings. Then, the limiting form of the optimal test is studied as the gap between the pre- and post-change means goes to zero, called the Mean-Change Test (MCT). It is shown that the MCT can be designed with only knowledge of the mean and variance of the pre-change distribution. The performance of the MCT is also characterized when the mean gap is moderate, under the additional assumption that the distributions of the observations have bounded support. The analysis is validated through numerical results for detecting a change in the mean of a beta distribution. The use of the MCT in monitoring pandemics is also demonstrated. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
31. Statistical co-analysis of high-dimensional association studies
- Author
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Liley, Albert James, Wallace, Chris, Mckinney, Eoin, and Todd, John Andrew
- Subjects
572.8 ,genetics ,disease heterogeneity ,multivariate Gaussian ,statistical methods ,two-stage association testing ,gwas ,non-parametric methods ,false discovery rate ,genetic risk scores ,lasso ,penalised regression ,two-groups model ,empirical Bayes ,statistics ,biostatistics ,autoimmune disease ,juvenile idiopathic arthritis ,type 1 diabetes ,autoimmune thyroid disease ,shared controls ,autoantibody ,statistical leverage ,effect size distribution - Abstract
Modern medical practice and science involve complex phenotypic definitions. Understanding patterns of association across this range of phenotypes requires co-analysis of high-dimensional association studies in order to characterise shared and distinct elements. In this thesis I address several problems in this area, with a general linking aim of making more efficient use of available data. The main application of these methods is in the analysis of genome-wide association studies (GWAS) and similar studies. Firstly, I developed methodology for a Bayesian conditional false discovery rate (cFDR) for levering GWAS results using summary statistics from a related disease. I extended an existing method to enable a shared control design, increasing power and applicability, and developed an approximate bound on false-discovery rate (FDR) for the procedure. Using the new method I identified several new variant-disease associations. I then developed a second application of shared control design in the context of study replication, enabling improvement in power at the cost of changing the spectrum of sensitivity to systematic errors in study cohorts. This has application in studies on rare diseases or in between-case analyses. I then developed a method for partially characterising heterogeneity within a disease by modelling the bivariate distribution of case-control and within-case effect sizes. Using an adaptation of a likelihood-ratio test, this allows an assessment to be made of whether disease heterogeneity corresponds to differences in disease pathology. I applied this method to a range of simulated and real datasets, enabling insight into the cause of heterogeneity in autoantibody positivity in type 1 diabetes (T1D). Finally, I investigated the relation of subtypes of juvenile idiopathic arthritis (JIA) to adult diseases, using modified genetic risk scores and linear discriminants in a penalised regression framework. The contribution of this thesis is in a range of methodological developments in the analysis of high-dimensional association study comparison. Methods such as these will have wide application in the analysis of GWAS and similar areas, particularly in the development of stratified medicine.
- Published
- 2017
- Full Text
- View/download PDF
32. Efficiently transporting causal direct and indirect effects to new populations under intermediate confounding and with multiple mediators.
- Author
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Rudolph, Kara E and Díaz, Iván
- Subjects
- *
ATTRIBUTION (Social psychology) , *STATISTICAL models - Abstract
The same intervention can produce different effects in different sites. Existing transport mediation estimators can estimate the extent to which such differences can be explained by differences in compositional factors and the mechanisms by which mediating or intermediate variables are produced; however, they are limited to consider a single, binary mediator. We propose novel nonparametric estimators of transported interventional (in)direct effects that consider multiple, high-dimensional mediators and a single, binary intermediate variable. They are multiply robust, efficient, asymptotically normal, and can incorporate data-adaptive estimation of nuisance parameters. They can be applied to understand differences in treatment effects across sites and/or to predict treatment effects in a target site based on outcome data in source sites. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
33. Risk Assessment in Monitoring of Water Analysis of a Brazilian River.
- Author
-
Brandão, Luciene Pires, Silva, Vanilson Fragoso, Bassi, Marcelo, and de Oliveira, Elcio Cruz
- Subjects
- *
WATER analysis , *BIOCHEMICAL oxygen demand , *MOLARITY , *RISK assessment , *ESCHERICHIA coli - Abstract
This study aimed to introduce non-parametric tests and guard bands to assess the compliance of some river water properties with Brazilian environmental regulations. Due to the heterogeneity of the measurands pH, Biochemical Oxygen Demand (BOD), manganese molar concentration, and Escherichia coli, which could be wrongly treated as outliers, as well as the non-Gaussian data, robust methods were used to calculate the measurement uncertainty. Next, based on guard bands, the compliance assessment was evaluated using this previous uncertainty information. For these four measurands, partial overlaps between their uncertainties and the specification limit could generate doubts about compliance. The non-parametric approach for calculating the uncertainty connected to the guard bands concept classified pH and BOD as "conform", with a risk to the consumer of up to 4.0% and 4.9%, respectively; in contrast, manganese molar concentration and Escherichia coli were "not conform", with a risk to the consumer of up to 25% and 7.4%, respectively. The methodology proposed was satisfactory because it considered the natural heterogeneity of data with non-Gaussian behavior instead of wrongly excluding outliers. In an unprecedented way, two connected statistical approaches shed light on the measurement uncertainty in compliance assessment of water analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
34. A Random Forest-Based Genome-Wide Scan Reveals Fertility-Related Candidate Genes and Potential Inter-Chromosomal Epistatic Regions Associated With Age at First Calving in Nellore Cattle.
- Author
-
Alves, Anderson Antonio Carvalho, da Costa, Rebeka Magalhães, Fonseca, Larissa Fernanda Simielli, Carvalheiro, Roberto, Ventura, Ricardo Vieira, Rosa, Guilherme Jordão de Magalhães, and Albuquerque, Lucia Galvão
- Subjects
CATTLE breeds ,CATTLE ,GENES ,GENOMICS ,CATTLE fertility ,GENOME-wide association studies ,CATTLE genetics ,SOMATIC cell nuclear transfer - Abstract
This study aimed to perform a genome-wide association analysis (GWAS) using the Random Forest (RF) approach for scanning candidate genes for age at first calving (AFC) in Nellore cattle. Additionally, potential epistatic effects were investigated using linear mixed models with pairwise interactions between all markers with high importance scores within the tree ensemble non-linear structure. Data from Nellore cattle were used, including records of animals born between 1984 and 2015 and raised in commercial herds located in different regions of Brazil. The estimated breeding values (EBV) were computed and used as the response variable in the genomic analyses. After quality control, the remaining number of animals and SNPs considered were 3,174 and 360,130, respectively. Five independent RF analyses were carried out, considering different initialization seeds. The importance score of each SNP was averaged across the independent RF analyses to rank the markers according to their predictive relevance. A total of 117 SNPs associated with AFC were identified, which spanned 10 autosomes (2, 3, 5, 10, 11, 17, 18, 21, 24, and 25). In total, 23 non-overlapping genomic regions embedded 262 candidate genes for AFC. Enrichment analysis and previous evidence in the literature revealed that many candidate genes annotated close to the lead SNPs have key roles in fertility, including embryo pre-implantation and development, embryonic viability, male germinal cell maturation, and pheromone recognition. Furthermore, some genomic regions previously associated with fertility and growth traits in Nellore cattle were also detected in the present study, reinforcing the effectiveness of RF for pre-screening candidate regions associated with complex traits. Complementary analyses revealed that many SNPs top-ranked in the RF-based GWAS did not present a strong marginal linear effect but are potentially involved in epistatic hotspots between genomic regions in different autosomes, remarkably in the BTAs 3, 5, 11, and 21. The reported results are expected to enhance the understanding of genetic mechanisms involved in the biological regulation of AFC in this cattle breed. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
35. Statistical guided-waves-based structural health monitoring via stochastic non-parametric time series models.
- Author
-
Amer, Ahmad and Kopsaftopoulos, Fotis P
- Subjects
STRUCTURAL health monitoring ,CARBON fiber-reinforced plastics ,TIME series analysis ,STATISTICAL decision making ,PIEZOELECTRIC transducers ,ULTRASONIC waves ,SENSOR networks - Abstract
Damage detection in active-sensing, guided-waves-based structural health monitoring (SHM) has evolved through multiple eras of development during the past decades. Nevertheless, there still exist a number of challenges facing the current state-of-the-art approaches, both in the industry as well as in research and development, including low damage sensitivity, lack of robustness to uncertainties, need for user-defined thresholds, and non-uniform response across a sensor network. In this work, a novel statistical framework is proposed for active-sensing SHM based on the use of ultrasonic guided waves. This framework is based on stochastic non-parametric time series models and their corresponding statistical properties in order to readily provide healthy confidence bounds and enable accurate and robust damage detection via the use of appropriate statistical decision-making tests. Three such methods and corresponding statistical quantities (test statistics) along with decision-making schemes are formulated and experimentally assessed via the use of three coupons with different levels of complexity: an Al plate with a growing notch, a carbon fiber-reinforced plastic (CFRP) plate with added weights to simulate local damage, and the CFRP panel used in the Open Guided Waves project, all fitted with piezoelectric transducers under a pitch-catch configuration. The performance of the proposed methods is compared to that of state-of-the-art time-domain damage indices (DIs). The results demonstrate the increased detection sensitivity and robustness of the proposed methods, with better tracking capability of damage evolution compared to conventional approaches, even for damage-non-intersecting actuator–sensor paths. In particular, the Z statistic emerges as the best damage detection metric compared to conventional DIs, as well as the other proposed statistics. Overall, the proposed statistics in this study promise greater damage sensitivity across different components, with enhanced robustness to uncertainties, as well as user-friendly application. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
36. A Random Forest-Based Genome-Wide Scan Reveals Fertility-Related Candidate Genes and Potential Inter-Chromosomal Epistatic Regions Associated With Age at First Calving in Nellore Cattle
- Author
-
Anderson Antonio Carvalho Alves, Rebeka Magalhães da Costa, Larissa Fernanda Simielli Fonseca, Roberto Carvalheiro, Ricardo Vieira Ventura, Guilherme Jordão de Magalhães Rosa, and Lucia Galvão Albuquerque
- Subjects
beef cattle ,candidate genes ,ensemble learning ,fertility traits ,non-parametric methods ,physiological epistasis ,Genetics ,QH426-470 - Abstract
This study aimed to perform a genome-wide association analysis (GWAS) using the Random Forest (RF) approach for scanning candidate genes for age at first calving (AFC) in Nellore cattle. Additionally, potential epistatic effects were investigated using linear mixed models with pairwise interactions between all markers with high importance scores within the tree ensemble non-linear structure. Data from Nellore cattle were used, including records of animals born between 1984 and 2015 and raised in commercial herds located in different regions of Brazil. The estimated breeding values (EBV) were computed and used as the response variable in the genomic analyses. After quality control, the remaining number of animals and SNPs considered were 3,174 and 360,130, respectively. Five independent RF analyses were carried out, considering different initialization seeds. The importance score of each SNP was averaged across the independent RF analyses to rank the markers according to their predictive relevance. A total of 117 SNPs associated with AFC were identified, which spanned 10 autosomes (2, 3, 5, 10, 11, 17, 18, 21, 24, and 25). In total, 23 non-overlapping genomic regions embedded 262 candidate genes for AFC. Enrichment analysis and previous evidence in the literature revealed that many candidate genes annotated close to the lead SNPs have key roles in fertility, including embryo pre-implantation and development, embryonic viability, male germinal cell maturation, and pheromone recognition. Furthermore, some genomic regions previously associated with fertility and growth traits in Nellore cattle were also detected in the present study, reinforcing the effectiveness of RF for pre-screening candidate regions associated with complex traits. Complementary analyses revealed that many SNPs top-ranked in the RF-based GWAS did not present a strong marginal linear effect but are potentially involved in epistatic hotspots between genomic regions in different autosomes, remarkably in the BTAs 3, 5, 11, and 21. The reported results are expected to enhance the understanding of genetic mechanisms involved in the biological regulation of AFC in this cattle breed.
- Published
- 2022
- Full Text
- View/download PDF
37. Inferential Statistics
- Author
-
Wilcox, Rand R.
- Published
- 2021
- Full Text
- View/download PDF
38. Bank Efficiency Assessment: A Bayesian Approach (Case Study of the Selected Banks of Iran)
- Author
-
Mohammad Taghi Taghavifard, Reza Habibi, and Abbas Ali Yari
- Subjects
efficiency ,efficiency change ,productivity change ,non-performing loans (npls) ,bayesian approach ,gibbs sampling ,non-parametric methods ,Business ,HF5001-6182 ,Capital. Capital investments ,HD39-40.7 - Abstract
The purpose of this research is to measure the efficiency of selected Iranian banks from 2010 to 2016. We estimate efficiency, productivity and efficiency changes under the Bayesian setting. In this research, we consider the Non-Performing Loans (NPLs) of banks as bad outputs, while good outputs are loans, off balance sheet assets and securities. Also, variables such as number of employees, bank capital, fixed assets and deposits play inputs role. Results show that the productivity changes of selected Iranian banks are positive over the period of the study, which is mainly due to the improvement in technology like e-banking services, while efficiency changes continued to be negative over the same period. It is observed that the average efficiency for banks is 85 percent. The Karafarin bank has the largest efficiency among selected banks while Refah Kargaran bank efficiency has the smallest one. Results also show that, during the specified period, private banks have a few better efficiency estimate in comparison with the efficiency of state owned banks.
- Published
- 2020
- Full Text
- View/download PDF
39. An epistatic interaction between pre-natal smoke exposure and socioeconomic status has a significant impact on bronchodilator drug response in African American youth with asthma
- Author
-
J. Magaña, M. G. Contreras, K. L. Keys, O. Risse-Adams, P. C. Goddard, A. M. Zeiger, A. C. Y. Mak, J. R. Elhawary, L. A. Samedy-Bates, E. Lee, N. Thakur, D. Hu, C. Eng, S. Salazar, S. Huntsman, T. Hu, E. G. Burchard, and M. J. White
- Subjects
Epistatic interactions ,Non-parametric methods ,Asthma drug response ,Health disparities ,Pediatric asthma ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Analysis ,QA299.6-433 - Abstract
Abstract Background Asthma is one of the leading chronic illnesses among children in the United States. Asthma prevalence is higher among African Americans (11.2%) compared to European Americans (7.7%). Bronchodilator medications are part of the first-line therapy, and the rescue medication, for acute asthma symptoms. Bronchodilator drug response (BDR) varies substantially among different racial/ethnic groups. Asthma prevalence in African Americans is only 3.5% higher than that of European Americans, however, asthma mortality among African Americans is four times that of European Americans; variation in BDR may play an important role in explaining this health disparity. To improve our understanding of disparate health outcomes in complex phenotypes such as BDR, it is important to consider interactions between environmental and biological variables. Results We evaluated the impact of pairwise and three-variable interactions between environmental, social, and biological variables on BDR in 233 African American youth with asthma using Visualization of Statistical Epistasis Networks (ViSEN). ViSEN is a non-parametric entropy-based approach able to quantify interaction effects using an information-theory metric known as Information Gain (IG). We performed analyses in the full dataset and in sex-stratified subsets. Our analyses identified several interaction models significantly, and suggestively, associated with BDR. The strongest interaction significantly associated with BDR was a pairwise interaction between pre-natal smoke exposure and socioeconomic status (full dataset IG: 2.78%, p = 0.001; female IG: 7.27%, p = 0.004)). Sex-stratified analyses yielded divergent results for females and males, indicating the presence of sex-specific effects. Conclusions Our study identified novel interaction effects significantly, and suggestively, associated with BDR in African American children with asthma. Notably, we found that all of the interactions identified by ViSEN were “pure” interaction effects, in that they were not the result of strong main effects on BDR, highlighting the complexity of the network of biological and environmental factors impacting this phenotype. Several associations uncovered by ViSEN would not have been detected using regression-based methods, thus emphasizing the importance of employing statistical methods optimized to detect both additive and non-additive interaction effects when studying complex phenotypes such as BDR. The information gained in this study increases our understanding and appreciation of the complex nature of the interactions between environmental and health-related factors that influence BDR and will be invaluable to biomedical researchers designing future studies.
- Published
- 2020
- Full Text
- View/download PDF
40. Productivity of Services in the Countries of Central and Eastern Europe: Analysis Using Malmquist Indices
- Author
-
Alejandro Alcalá-Ordóñez, Francisco Alcalá-Olid, and Pablo Juan Cárdenas-García
- Subjects
productivity ,services ,Malmquist index ,DEA ,non-parametric methods ,Economics as a science ,HB71-74 - Abstract
This research aims to study the growth of productivity in the service sector in the former Central and Eastern European Countries (CEECs) and their determinants. For this purpose, non-parametric frontier techniques were used to measure the variations in productivity and determine the explanatory factors of these changes in total factor productivity; the methodology of the Malmquist index with output orientation and its decomposition in technical change, pure technical efficiency and scale efficiency was used for the period 2000–2019. The results obtained indicate that the productivity of services in the most recently incorporated countries grew by 1.3 per 100 on average per year compared to 1.6 per 100 in manufacturing. The most important driver of such growth was found to be improvement in technical change (frontier shift) rather than improvement in efficiency.
- Published
- 2023
- Full Text
- View/download PDF
41. A pilot study on the home range and movement patterns of the Andean Fox Lycalopex culpaeus (Molina, 1782) in Cotopaxi National Park, Ecuador.
- Author
-
Castellanos, Armando, Castellanos, Francisco X., Kays, Roland, and Brito, Jorge
- Subjects
- *
MAMMAL behavior , *NATIONAL parks & reserves , *PILOT projects , *TAGS (Metadata) - Abstract
This study reports movement patterns and home range estimates of an Andean fox (Lycalopex culpaeus) in Cotopaxi National Park in Ecuador, representing the first GPS-tagging of the species. The GPS functioned well during the 197-day tracking period. Home range sizes ranged between 4.9 and 8.1 km2, depending on the estimation method. Movement speeds averaged 0.17 km/h at day versus 0.87 km/h at night, and distance traveled averaged 0.23 km at day versus 0.89 km at night. These preliminary results highlight the importance of collecting unbiased, high-quality data which enables an enhanced understanding on mammal behavior and human/animal interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
42. Consistency of permutation tests of independence using distance covariance, HSIC and dHSIC.
- Author
-
Rindt, David, Sejdinovic, Dino, and Steinsaltz, David
- Subjects
- *
DEPENDENCE (Statistics) , *NULL hypothesis , *PERMUTATIONS - Abstract
The Hilbert–Schmidt independence criterion (HSIC) and its d‐variable extension dHSIC are measures of (joint) dependence between random variables. While combining these statistics with a permutation test has become a popular method of testing the null hypothesis of (joint) independence, it had thus far not been proved that this results in a consistent test. In this work, we provide a simple proof that the permutation test with the test statistic HSIC or dHSIC is indeed consistent when using characteristic kernels. That is, we prove that under each alternative hypothesis, the power of these permutation tests indeed converges to 1 as the sample size converges to infinity. Since the test is consistent for each number of permutations, we further give a brief discussion of how the number of permutations relates to the power of the test and how the number of permutations may be selected in practice. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
43. Estimating survival distributions for two-stage adaptive treatment strategies: A simulation study.
- Author
-
Vilakati, Sifiso, Cortese, Giuliana, and Dlamini, Thembelihle
- Subjects
RANDOMIZATION (Statistics) ,LEUKEMIA treatment ,KAPLAN-Meier estimator - Abstract
Inference following two-stage adaptive designs (also known as two-stage randomization designs) with survival endpoints usually focuses on estimating and comparing survival distributions for the different treatment strategies. The aim is to identify the treatment strategy(ies) that leads to better survival of the patients. The objectives of this study were to assess the performance three commonly cited methods for estimating survival distributions in two-stage randomization designs. We review three non-parametric methods for estimating survival distributions in two-stage adaptive designs and compare their performance using simulation studies. The simulation studies show that the method based on the marginal mean model is badly affected by high censoring rates and response rate. The other two methods which are natural extensions of the Nelson-Aalen estimator and the Kaplan-Meier estimator have similar performance. These two methods yield survival estimates which have less bias and more precise than the marginal mean model even in cases of small sample sizes. The weighted versions of the Nelson-Aalen and the Kaplan-Meier estimators are less affected by high censoring rates and low response rates. The bias of the method based on the marginal mean model increases rapidly with increase in censoring rate compared to the other two methods. We apply the three methods to a leukemia clinical trial dataset and also compare the results. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
44. A STATISTICAL ASSESSMENT ON ABRUPT CHANGE AND TREND ANALYSIS OF RICE PRODUCTION.
- Author
-
Kalpana, Polisetty, Kumar, Paidipati Kiran, and Chesneau, Christophe
- Subjects
SMALL business ,CREDIT risk - Abstract
The most common method for studying historical data is to use regression methods and predictive modeling on time series data. The parametric methodology for time series data analysis is a customary method when the data are available on a continuous scale. However, most of the time, the data availability may be on a categorical or ordinal scale. Hence, the nonparametric methodology is more rational in handling time series data. This study considers two prominent non-parametric methods, namely Pettitt's test and Buishand's range test. In particular, we examine an abrupt change in the annual data of rice production during the period 1980-2020 by these methods. The study continued to assess the performance of rice production with the presence and absence of trend as performed by the Mann-Kendall test and the trend measured by Sen's slope estimator. According to the findings, the second time period's average growth rate has improved slightly but not as significantly as the first time period's. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
45. Climate change impacts on the water flow to the reservoir of the Dez Dam basin
- Author
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Nima Norouzi
- Subjects
Global warming ,Climate change ,Non-parametric methods ,Flow regime ,Zagros region ,Water source ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
This study has led to changes in the Dez Dam water basin area in recent decades. Non-parametric Mann-Kendal trend test and two shift change point detection tests of Pettit and Buishand were applied to the discharge time-series at the outlet of Tire, Marbore, Sazar, and Bakhtiari sub-basins to identify monotonic and abrupt changes. The Mann-Kendall test showed a significant negative (decreasing) trend of the flow in three sub-basins. Investigation of the flow of Dez Basin in the past decades shows significant monotonic and abrupt changes, which are mostly toward decreasing the basin’s potential runoff. Considering this evidences, it is likely that the basin faces discharge reduction, and results emphasize on modification of water management strategies to adapt to climate change.
- Published
- 2020
- Full Text
- View/download PDF
46. TEST OF INTERACTION IN THE ANALYSIS OF MOLECULAR VARIANCE
- Author
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Bruno C., Videla M.E., and Balzarini M.
- Subjects
genetic variability ,non-parametric methods ,distances matrix ,amova ,Genetics ,QH426-470 - Abstract
The genomic diversity, expressed in the differences between molecular haplotypes of a group of individuals, can be divided into components of variability between and within some factor of classification of the individuals. For such variance partitioning, molecular analysis of variance (AMOVA) is used, which is constructed from the multivariate distances between pairs of haplotypes. The classical AMOVA allows the evaluation of the statistical significance of two or more hierarchical factors and consequently there is no interaction test between factors. However, there are situations where the factors that classify individuals are crossed rather than nested, that is, all the levels of a factor are represented in each level of the other one. This paper proposes a statistical test to evaluate the interaction between crossed factors in a Non-Hierarchical AMOVA. The null hypothesis of interaction establishes that the molecular differences between individuals of different levels of a factor are the same for all the levels of the other factor that classifies them. The proposed analysis of interaction in a Non-Hierarchical AMOVA includes: calculation of the distance matrix and partition of it into blocks, subsequent calculation of residuals and analysis of non-parametric variance on the residuals. Its implementation is illustrated in simulated and real scenarios. The results suggest that the proposed interaction test for the Non-Hierarchical AMOVA presents high power.
- Published
- 2019
- Full Text
- View/download PDF
47. Risk Assessment in Monitoring of Water Analysis of a Brazilian River
- Author
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Luciene Pires Brandão, Vanilson Fragoso Silva, Marcelo Bassi, and Elcio Cruz de Oliveira
- Subjects
biochemical oxygen demand ,manganese molar concentration ,guard bands ,pH ,non-parametric methods ,Escherichia coli ,Organic chemistry ,QD241-441 - Abstract
This study aimed to introduce non-parametric tests and guard bands to assess the compliance of some river water properties with Brazilian environmental regulations. Due to the heterogeneity of the measurands pH, Biochemical Oxygen Demand (BOD), manganese molar concentration, and Escherichia coli, which could be wrongly treated as outliers, as well as the non-Gaussian data, robust methods were used to calculate the measurement uncertainty. Next, based on guard bands, the compliance assessment was evaluated using this previous uncertainty information. For these four measurands, partial overlaps between their uncertainties and the specification limit could generate doubts about compliance. The non-parametric approach for calculating the uncertainty connected to the guard bands concept classified pH and BOD as “conform”, with a risk to the consumer of up to 4.0% and 4.9%, respectively; in contrast, manganese molar concentration and Escherichia coli were “not conform”, with a risk to the consumer of up to 25% and 7.4%, respectively. The methodology proposed was satisfactory because it considered the natural heterogeneity of data with non-Gaussian behavior instead of wrongly excluding outliers. In an unprecedented way, two connected statistical approaches shed light on the measurement uncertainty in compliance assessment of water analysis.
- Published
- 2022
- Full Text
- View/download PDF
48. Assessment of parametric and non-parametric methods for prediction of quantitative traits with non-additive genetic architecture.
- Author
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Salehi, Abdolreza, Bazrafshan, Maryam, and Abdollahi-Arpanahi, Rostam
- Subjects
- *
QUANTITATIVE research , *RANDOM forest algorithms , *CHROMOSOMES , *EVALUATION methodology , *HERITABILITY - Abstract
Whole genome evaluation of quantitative traits using suitable statistical methods enables researchers to predict genomic breeding values (GEBVs) more accurately. Recent studies suggested that the ability of methods in terms of predictive performance may depend on the genetic architecture of traits. Therefore, when choosing a statistical method, it is essential to consider the genetic architecture of the target traits. Herein, the performance of parametric methods i.e. GBLUP and BayesB and non-parametric methods i.e. Bagging GBLUP and Random Forest (RF) were compared for traits with different genetic architecture. Three scenarios of genetic architecture, including purely Additive (Add), purely Epistasis (Epis) and Additive-Dominance-Epistasis (ADE) were considered. To this end, an animal genome composed of five chromosomes, each chromosome harboring 1000 SNPs and four QTL was simulated. Predictive accuracies in the first generation of testing set under Additive genetic architectures for GBLUP, BayesB, Baging GBLUP and RF were 0.639, 0.731, 0.633 and 0.548, respectively, and were 0.278, 0.330, 0.275 and 0.444 under purely Epistatic genetic architectures. Corresponding values for the Additive-Dominance-Epistatic structure also were 0.375, 0.448, 0.369 and 0.458, respectively. The results showed that genetic architecture has a great impact on prediction accuracy of genomic evaluation methods. When genetic architecture was purely Additive, parametric methods and Bagging GBLUP were better than RF, whereas under Epistatic and Additive-Dominance-Epistatic genetic architectures, RF delivered better predictive performance than the other statistical methods. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
49. Exact tables for the Friedman rank test: Case with ties.
- Author
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LÓPEZ-VÁZQUEZ, CARLOS, TASISTRO, ANDRÓMACA, and HOCHSZTAIN, ESTHER
- Subjects
- *
FRIEDMAN test (Statistics) , *TEXTBOOKS - Abstract
Exact tables for the case without ties of the Friedman statistic test proposed have been available since its inception. A modified statistic suitable for the case with ties has been derived 30 years later, and it appears in a text book nearly after 40 years. However, exact tables for the case of ties were never offered. Here we present for the first time a reduced set of exact tables for such a case, thus filling a gap. If a problem allows ties, the proper exact tables should be used thus disregarding other workarounds commonly suggested in the literature. The availability of exact tables for the case of ties is relevant for applied research because an hypothesis test decision when ties occur may be different if tables for the case without ties are used instead. We illustrate the effect of using the correct tables with both an example and a real data case study in the context of geoportals navigation analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2021
50. A novel non-parametric statistical method in reliability theory: Mathematical characterization and analysis of asymmetric data in the fields of biological sciences and engineering.
- Author
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Al-Essa LA, Etman WBH, Eliwa MS, El-Morshedy M, and El-Sagheer RM
- Abstract
In recent decades, strategies devised to address challenges in life testing have noticeably veered away from those designed for related yet more intricate issues. The increasing complexity of data generated daily across practical fields has given rise to a novel realm in reliability that includes life classes and specific probability distributions. This study serves as an illustration of the effectiveness of integrating the goodness-of-fit technique into life testing quandaries, resulting in more efficient processes comparable to or surpassing traditional methods. Furthermore, these techniques exhibit potential for enhanced performance, particularly when dealing with smaller sample sizes. The comparison between the Exponential Better than Used in Increasing Convex in Laplace Transform Order (EBUCL) test statistic and a distinct goodness-of-fit test statistic upholds an approach leaning towards normalcy. Analysis encompassing powers, Pitman asymptotic effectiveness, and critical points, as well as the exploration of methodologies for handling suppressed data, has been undertaken. Additionally, a simulation study has been conducted to examine the study's motivations across various sample sizes. The results derived from our experiments hold practical implications for both bioscience and engineering sustainability data analyses., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
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