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The interpretation of glass evidence is crucial to the accurate appraisal of the evidential value of the analytical results. Frequently, the first step in this assessment is a comparison between the analytical results of the recovered and control glass fragments to determine whether they could have come from the same source of glass. A number of different methods are available depending on the type of analytical test performed. The second step is to determine the evidential value of these findings. This involves consideration of a number of factors, including the amount of matching and nonmatching glass found, the frequency of the matching glass, the probability of glass being transferred given the particular case scenario, and the amount of background glass found on a random person. The assessment of the evidential value can be made in an essentially subjective manner or by using a more formal framework, such as the calculation of the likelihood ratio (LR). Methods to report these findings are also presented.

Aim: To compare the amount of extruded debris with three endodontic NiTi engine driven systems, Protaper Next, Hyflex CM and EdgeFile X7. Material and Methods: A total number of 42 freshly extracted human premolars were selected. Teeth were divided randomly into three equal groups (14 teeth each group) according to type of Ni-Ti rotary file system; (A) Protaper Next, (B) Hyflex CM and (C) EdgeFile X7. Standard Access cavity prepared and checked for patency using K file #10 and #15. Root canal instrumentation on the single canal lower premolars was done. Debris was collected after root canal instrumentation in pre-weighed Eppendorf tubes. The Eppendorf tubes were weighed 2 times on the analytical balance. First weight: Before instrumentation. Second weight: After evaporation of moisture and irrigant and incubation. Welch test was used for comparison between the three groups. Results: There was no statistically significant difference between the amounts of debris extrusion of the three groups Conclusion: All endodontic rotary instruments tested produced apical extrusion of debris.

Since COVID-19 pandemic entered Indonesia, mental health experts have also investigated the increase in psychological problems, one of which is anxiety. The fear of being infected or unknowingly infecting other people is a major source of anxiety during COVID-19 pandemic. This study aims to describe the differences in early adult anxiety during COVID-19 in terms of gender. This study is a comparative study at the early adult development stage in Indonesia, obtained through random sampling. The sample of this study was 206 people (male = 66; female = 140). The analysis technique used is the Welch Test on the Rasch model with the help of WINSTEPS Version 3.73. The analysis showed that there was no difference in anxiety during COVID-19 between male and female early adulthood. This condition is caused by early adulthood male and female depending on the internet and smartphones to find information when quarantining at home, increasing feelings of anxiety about being infected with COVID-19. The implementation of guidance and counseling is discussed further

PurposeTo characterize the prevalence of work-related musculoskeletal disorders (MSD), symptoms, and risk factors among ophthalmologists.MethodsAn online survey was distributed to ophthalmologist members of the Maryland Society of Eye Physicians and Surgeons. The survey consisted of 34 questions on respondent demographics, practice characteristics, pain, and effects of MSD on their practice patterns. Participants were excluded if they were not ophthalmologists or if they had MSD symptoms prior to the start of their ophthalmology career. Demographics and practice patterns were compared for those with or without MSD symptoms using the Welch t test and the Fisher exact test.ResultsThe survey was completed by 127 of 250 active members (response rate, 51%). Of the 127, 85 (66%) reported experiencing work-related pain, with an average pain level of 4/10. With regard to mean age, height, weight, years in practice, number of patients seen weekly, and hours worked weekly, there was no difference between respondents reporting pain and those without. Those reporting MSD symptoms spent significantly more time in surgery than those who did not (mean of 7.9 vs 5.3 hours/week [P < 0.01]). Fourteen percent of respondents reported plans to retire early due to their symptoms.ConclusionsA majority of respondents experienced work-related MSD symptoms, which was associated with time spent in surgery. Modifications to the workplace environment focusing on ergonomics, particularly in the operating room, may benefit ophthalmologists.

Using a Logistic regression model the present study investigates the important factors that influence on ease of doing business by the women entrepreneurs. The respondents are from the four different backward regions in West Bengal, India. The goodness of fit of the model is checked in terms of the Hosmer–Lemeshow test. Moreover, a large share of the women-owned business is a single person enterprise, generates lower revenues, and is smaller in size. The study shows that most women are engaged in small entrepreneurs to help their families financially. Though, women entrepreneurs are facing challenges of financing and non-cooperation from their family members. Even from non-cooperation from the family, they are engaged in entrepreneurship after managing their households’ work. The level of productivity will be enhanced significantly in case easy access to credit and support received from the family members. The support may be in terms of mental as well by helping in households’ work. Further, the application of the Welch’s t-test shows the non-existence of a significant difference in income level among the two groups, who have faced complexities and who have no complexities into running the entrepreneurship. To improve the socio-economic status of the female counterpart of the society, initiatives from the grassroots level are absolutely essential.

Although unsuccessful bids are usually discarded once the bids are opened under the typical lowest-price sealed-bid project award auction environment, considering efforts and resources expended by responsive and responsible bidders, it is likely that not only a successful bid but also unsuccessful bids can convey important information about the project at hand. This article documents an effort to answer the question that whether projects that receive more dispersed estimates at the bidding stage are more likely to experience greater project cost changes. Taking collective intelligence as the theoretical framework, a total of 210 projects conducted by the Ohio Department of Transportation between 2008 and 2018 were analyzed to investigate the relationship between the coefficients of variation of bids and project final costs. It was found that large projects with above-average coefficients of variation of bids showed greater deviations from original award amounts than large projects with below-average coefficients of variation. The finding enables project owners to study the projects before execution by recouping valuable insights from the community of bidders on the possibility of greater project cost changes faced by the planned projects without complex and mathematically rigorous models.

In this study, we analyzed the changes in the average daily, monthly, seasonal, and annual surface air temperatures based on the temperature data obtained from seven stations (1 January 2005&ndash, 31 December 2019, 15 years) belonging to the central Baltic area (Stockholm, Tallinn, Helsinki, Narva, P&auml, rnu, Tartu, and V&otilde, ru). The statistical analysis revealed that there was a strong correlation between the daily average surface air temperature of the studied cities (range: 0.95&ndash, 0.99). We analyzed the frequency distribution of the average surface air temperatures in addition to the Kruskal&ndash, Wallis and Dunn&rsquo, s tests (significance level of 0.05) to demonstrate that the difference in air temperatures between Narva, Tallinn, Tartu, and Stockholm are critical. The Welch&rsquo, s -test (significance level 0.05), used to study the differences in the average monthly air temperature of the cities in question, showed that the surface air temperatures in Stockholm do not differ from Tallinn air temperatures from May to August. However, the surface air temperatures of Narva were similar to those of Tallinn in September. According to our results, the trends in the changes of monthly average surface air temperatures have a certain course during the year (ranging from 1.8 &deg, C (Stockholm) to 4.5 &deg, C (V&otilde, ru and Tartu) per decade in February). During the entire study period, in addition to February, the surface air temperature increased in all the studied cities in March, May, June, and December, and the surface air temperature did not increase in January or from July to October. During the study period, the average annual surface air temperature in the cities of the central Baltic area increased by 0.43 &deg, C per decade. The results also confirm that the surface air temperature in the study area is changing differently in different cities. The acceleration of the surface air temperature is very alarming and requires a significant intensification of the measures taken to slow down the temperature rise.

Research background: Recent research conducted in the field of entrepreneurship focuses on a better understanding of specific features of family businesses, which, according to estimates, make up 55–90 % of all business entities in EU member states. Foreign studies emphasise the greater resilience of family businesses in the face of adverse changes in their business environment, their ability of long-term survival and a higher degree of socially responsible behaviour. Purpose of the article: The main objective of this article is to find out whether there are statistically significant differences in performance between family and non-family businesses. The results will be used to determine whether the performance of family businesses differs from that of non-family businesses and to identify the specific features of family business. This information will also be used to enhance our knowledge of family entrepreneurship and to determine whether the conclusions of foreign studies are also valid for family businesses in the Czech Republic. Methods: We compared the results of two sets of data with financial results to identify differences in the performance of family and non-family businesses. Due to the fact that there is currently no register of family businesses, we first had to identify which are family businesses and complement them with non-family businesses. We used the accounting data of almost 8,000 businesses from the years 2014–2018 for this analysis. We defined 44 indicators and tested them using Welch’s t-test. Findings & value added: The analysed sample consists predominantly of small businesses. We identified a total of 30 ratios whose values differ statistically at a significance level of 5 %, for example current assets to sales, retained earnings to total assets and labour cost to sales. We can deduce from the results that there are differences in performance between family and non-family businesses.

Researchers are generally required to report and interpret effect sizes and associated confidence intervals. When comparing two independent groups, the most commonly used estimator of effect size is Cohen’s ds where sample mean difference is divided by the pooled standard deviation. However, computing the pooled error term is not valid when both groups do not share common population variances. Furthermore, the assumption of equal population variances is unlikely in many psychological fields. Consequently, researchers shift to the use of Welch’s t-test over Student’s t-test in the context of hypothesis testing. Meanwhile, the question which effect size to report when equal variances are not assumed remains open. Based on Monte Carlo simulations, we compare Hedges’ gs (i.e. Cohen’s ds with correction for bias) to Glass’s gs, Shieh’s gs and Hedges’ g_s^*. Comparisons are made under normality as well as under realistic deviations from the assumptions of normality and equal variances. Although it is not directly related with Welch’s t-test (unlike Shieh’s gs), we recommend the use of Hedges’ g_s^* because it shows better properties than all other estimators. Practical recommendations, R package and Shiny App in order to compute effect size estimators and confidence intervals are provided.

A transformation of the Welch statistic to compare means is proposed to correct skewness and kurtosis of parent populations. The results show that this transformation seems to improve the performance of the test in heavy-tailed distributions more than other transformations focused only on skewness. The proposed test outperforms the Welch test in asymmetric heavy-tailed distributions with high heteroscedasticity and it behaves better than the Johnson’s transformation trimmed mean Welch test in normal, near-normal and light-tailed distributions. It may also be a better option when some of the distributions are heavy-tailed and some light-tailed.

Objective: The aim of the study was to compare and evaluate Hyflex CM files and M-Pro files versus Protaper Next files regarding the amount of apically extruded debris in the mesial root canals of mandibular molars.Methodology: Sixty three human permanent mandibular molars were utilized in the study. Empty Eppendorf tubes were weighed using an analytical balance three times and an average weight was calculated (W1). Then, a hole was created in the stopper of the Eppendorf tubes and mesial roots were inserted. The roots were randomly assigned into 3 groups according to the instrumentation technique used: Group I: Protaper Next (n=21), Group II: Hyflex (n=21) and Group III: M-Pro (n=21). Distilled water was used as an irrigant in all groups. After instrumentation, the vials were placed in an incubator for 3 days and the apically extruded debris collected in the Eppendorf tubes were weighed again (W2) after instrumentation. Welch test was used for comparison between the three groups.Results: There was no statistically significant difference between the amount of debris extrusion of the three groups (P=0.204). Conclusion: Within the limitation of this study it was concluded that all systems were associated with extrusion of debris.

The current study aims at discriminating cotton and woolen textile fibers from dye using UV-Vis spectroscopy and chemometrics methods. For extraction of the dye from fibers, seven solvent systems have been used, and different extraction conditions have also been tested. Two different approaches, i.e., a visual comparison of peaks and chemometric analysis, have been proposed to differentiate between the textile fibers. The comparison of peaks obtained through UV-Vis spectra provides the discrimination power of 83.6% for cotton fibers and 94.3% for the woolen fibers. However, the incorporation of chemometrics has further improved the discrimination power to 100% for cotton and 98.1% for woolen fibers. The discrimination of 100% is achieved with nonsignificant values of the Welch's t-test, which illustrates that all samples are discriminated.

El plagio académico es una práctica común entre estudiantes universitarios. Tradicionalmente esta temática ha sido abordada a través de estudios que determinan los factores generadores de la misma, sin ahondar en estrategias efectivas que prevengan dichas prácticas. Por tanto, para este estudio se utilizó una estrategia novedosa llamada i_map, que reduce el plagio académico a través del fortalecimiento de las habilidades de búsqueda y manejo de información, documentación del proceso de investigación y generación de ideas propias por parte del estudiante.El objetivo de este estudio es determinar la efectividad del i_map en la prevención del plagio académico y compararla con estrategias tradicionales como el reforzamiento en el uso de paráfrasis y citas textuales. La investigación fue desarrollada en tres espacios pedagógicos de la Carrera de Ciencias Naturales del CUED-UPNFM, cada espacio fue diferenciado según el tipo de estrategia utilizada (i_map, talleres de paráfrasis y citas textuales, equipo control) para la elaboración de ensayos académicos. En total fueron analizados 74 ensayos. El análisis de los datos fue realizado a través de un ANOVA de factor único y Welch test. Los niveles más bajos de plagio (p=0.0003246) y los valores medios más altos de fuentes académicas citadas (p=0.0100) fueron registrados en los trabajos de los estudiantes que utilizaron el i_map. Este estudio concluye la efectividad, estadísticamente significativa, del uso del i_map en la prevención de plagio académico, por lo que sugerimos la inclusión de esta estrategia como herramienta para prevenir dicha práctica y a la vez mejorar la redacción de asignaciones escritas.

The aim of this study was to evaluate if the configuration of canal orifices can predict the presence of a second mesiobuccal canal (MB2) in maxillary second molars with fused roots.Maxillary second molars with fused roots (N = 150) were scanned in a micro-computed tomographic device (pixel size = 9 μm) and evaluated regarding the root fusion type and the incidence of the MB2 canal. The centers of the canal orifices were connected, and the angles formed by the intersection of these lines as well as their distances were measured and statistically compared (1-way analysis of variance). Specimens were then assigned to 2 groups according to the presence (n = 65) or absence (n = 50) of the MB2 canal and compared regarding the angles and interorifice distances using the Welch t test. A binary logistic regression model estimated the association between the interorifice distance, the fusion type, and the presence of the MB2 canal, whereas receiver operating characteristic curve analysis was performed to evaluate the diagnostic abilities of significant variables. The significance level was set at 5%.The most common fusion types were 1 and 6, and MB2 canal incidence was 47.3%. No statistical difference was observed in the angles or interorifice distances among teeth with different fusion types (P.05). Distances from the mesiobuccal (MB) to the distobuccal and palatal (P) canal orifices as well as the MB and P angles were significantly higher in the presence of an MB2 canal (P.05). A binary logistic regression model revealed that MB-distobuccal and MB-P distances were significant in the presence of an MB2 canal (P.05). Receiver operating characteristic analysis indicated that MB-P distance had acceptable diagnostic accuracy for the prediction of MB2 canal presence. Sensitivity (specificity) calculated from the MB-P distances of 4.0, 4.5, and 5.0 mm were 89.2% (36.5%), 76.9% (58.4%), and 44.4% (71.4%), respectively.MB-P interorifice distance is a strong predictor of the presence of the MB2 canal in maxillary second molars with fused roots.

Background: On February 26, 2020, the first case of coronavirus disease 2019 (COVID-19) was detected in Israel. The Ministry of Health (MoH) instructed people to take isolation measures and restrict their movement. Similarly, there was a gradual decrease in the number of visits to our emergency department (ED). Objectives: To describe the decline in the referrals to the ED and in-hospital beds occupancy during the COVID-19 pandemic and to compare it to the H1N1 2009 pandemic. Methods: Employing a cross-sectional epidemiologic study, the pattern of visits to the ED during the COVID-19 was compared with the pattern of visits during the 2009 H1N1 pandemic, as well as a year without a pandemic. The data was adjusted to consider changes in population size. The Welch t test for unpaired, unequal samples was used to analyze the data. Results: Within 2 months of the COVID-19 outbreak, the average number of visits to the ED dropped by 30.2% and the hospital occupancy by 29.2% (a minimum of 57%), compared to the same period, the year before. In comparison to the same period during the H1N1 outbreak, we witnessed a significant decline in the number of visits to the ED during the COVID-19 outbreak. Conclusion: The behavior of people during the COVID-19 pandemic was different from their behavior during the H1N1 pandemic. People seemed to avoid visiting the ED. The boundary between precaution and panic in the generation of the media could be very thin. Decision-makers must take this into account.

Objectives To better characterize the formation of false memories in older adults, we conducted a study using a French adaptation of the misinformation paradigm from Loftus, Levidow, and Duensing (1992). We aimed to show higher false memory production in older than in younger adults. Method One hundred and four younger adults (18–30 years) and 104 older adults (70–95 years) took part in the study. Participants were presented with a misinformation paradigm through the viewing of a short video followed by a questionnaire containing misinformation about the film. After a short delay (45 min), they performed a recognition task. Results Contrary to our hypothesis, the results analyzed with a Welch t test did not reveal a greater misinformation effect in older adults than in younger adults. Results were reanalyzed using the equivalence test which indicated that younger and older adults are statistically equivalent and not statistically different. Discussion The equivalence test helped to clarify the contradictory results of the literature. Furthermore, such results show the interest to reconsider misinformation effect in aging.

Objective To evaluate public's interest in contraceptive options following heightened focus on a repeal of the Affordable Care Act (ACA) since the 2016 United States presidential election. Study design We monitored the fraction of Google searches emerging from the United States for the three most popular reversible contraceptive methods — oral contraceptives, intrauterine devices (IUDs) and condoms — from January 1, 2004, through October 31, 2017 (1 year after the presidential election). Results IUD searches were cumulatively 15% (95% CI: 10 to 20) higher than expected the year following the 2016 election, reflecting 10 to 21 million excess searches. IUD searches were statistically significantly higher in all states, except NV, and were consistent across states won by Trump or Clinton (Welch t test=0.60, p=.548). Conversely, searches for oral contraceptives and condoms remained stable (0%; 95% CI: −2 to 1) or declined (−4%; 95% CI: −5 to −2), respectively, following the election. Conclusions The etiology of increased searches for IUDs is likely multifaceted. However, it may largely be because IUDs will confer continued protection even after an ACA repeal, thereby providing a medical hedge against a possible repeal. Regardless, these data suggest the heightened focus on an ACA repeal is a concern to the record number of Americans seeking out information about IUDs.

Purpose: To assess the impact of COVID-19 on the overall volume of IR outpatient-based evaluation and management encounters (E&M) and to demonstrate the role of telehealth in offsetting the loss of volume caused by COVID-19 Materials and Methods: A retrospective review of IR E&M in a large academic health system between January 6, 2020 and August 23, 2020, was conducted using the same time period in 2019 as a historical control. IR encounters were collected by gathering the weekly volume of submitted E&M current procedural technology (CPT) codes from the IR division. IR encounters were classified as outpatient or telehealth E&M. The E&M volume in 2019 was used as a historical control. Data were divided into three periods: pre-surge (January 6–March 15, 2020), surge (March 16–June 7, 2020), and recovery (June 8–August 23, 2020). The mean encounters per week during the surge and recovery periods were compared to the pre-surge baseline using a Welch t test for 2020 data, and the same comparison was made for 2019 data for a historical control. Results: During the surge period, outpatient E&M volume, inclusive of telemedicine, fell by 55.8% relative to the pre-surge 2020 baseline. The volume grew steadily during the recovery period but remained 19.8% below pre-surge 2020 levels. The surge and recovery mean weekly E&M volume was significantly different from the equivalent periods in 2019 (P < 0.001 and P = 0.02, respectively). During the surge, telemedicine comprised 44.6% of the total outpatient E&M. The contribution of telemedicine gradually fell over the recovery period, comprising just 11.5% in the final week of the study, and 16.7% during the recovery. Outpatient E&M reached a nadir during the week of April 13th, reflecting a 70.6% decline relative to the same period in 2019. The recovery period demonstrated a gradual increase in outpatient E&M with a decline in telehealth encounters balanced by a growth of in-person visits. During the last week of the recovery period (week of 8/17), outpatient in-person E&M had recovered to 2019 levels, and with the inclusion of telehealth exceeded E&M in 2019 for the same period by 93.3%. Conclusions: Telemedicine becomes an important way to maintain outpatient E&M volume in the event of a pandemic when social distancing and stay-at-home orders preclude face-to-face visits. Revenue from outpatient E&M may help bridge the gap until resumption of elective procedures and recovery of procedural case volume.

Nguyen et al. (2016) offered advice to researchers in the commonly-encountered situation where they are interested in testing for a difference in central tendency between two populations. Their data and the available literature support very simple advice that strikes the best balance between ease of implementation, power and reliability. Specifically, apply Satterthwaite’s test, with preliminary ranking of the data if a strong deviation from normality is expected, or is suggested by visual inspection of the data. This simple guideline will serve well except when dealing with small samples of discrete data, when more sophisticated treatment may be required.

This study investigates how outliers of different magnitude impact the robustness of the twosample t-test. A simulation study approach is used to analyze the behavior of type I error rates when outliers are added to generated data. Outliers may distort parameter estimates such as the mean and variance and cause misleading test results. Previous research has shown that Welch’s ttest performs better than the traditional Student’s t-test when group variances are unequal. Therefore these two alternative statistics are compared in terms of type I error rates when outliers are added to the samples. The results show that control of type I error rates can be maintained in the presence of a single outlier. Depending on the magnitude of the outlier and the sample size, there are scenarios where the t-test is robust. However, the sensitivity of the t-test is illustrated by deteriorating type I error rates when more than one outlier are included. The comparison between Welch’s t-test and Student’s t-test shows that the former is marginally more robust against outlier influence.

The Test Vector Leakage Assessment (TVLA) methodology is a qualitative tool relying on Welch’s T-test to assess the security of cryptographic implementations against side-channel attacks. Despite known limitations (e.g., risks of false negatives and positives), it is sometimes considered as a pass-fail test to determine whether such implementations are “safe” or not (without clear definition of what is “safe”). In this note, we clarify the limited quantitative meaning of this test when used as a standalone tool. For this purpose, we first show that the straightforward application of this approach to assess the security of a masked implementation is not sufficient. More precisely, we show that even in a simple (more precisely, univariate) case study that seems best suited for the TVLA methodology, detection (or lack thereof) with Welch’s T-test can be totally disconnected from the actual security level of an implementation. For this purpose, we put forward the case of a realistic masking scheme that looks very safe from the TVLA point-of-view and is nevertheless easy to break. We then discuss this result in more general terms and argue that this limitation is shared by all “moment-based” security evaluations. We conclude the note positively, by describing how to use moment-based analyses as a useful ingredient of side-channel security evaluations, to determine a “security order”.

This article proposes a useful extension of the ANOVA F-test for examining mean differences for evaluating the comparability of standardized mean effects. The equivalence procedure presumably suffers from the same disadvantage as the traditional ANOVA F-statistic regarding the violations of homogeneous variance assumption. In view of the absence of vital clarification for theory development and supportive technique, this article provides a critical exposition of the extended Welch test for the equivalence of standardized means. To enhance the usefulness of equivalence testing, the theoretical properties and practical implications of the Welch-type procedure are demonstrated. Moreover, the corresponding power and sample size algorithms are described for advance planning of equivalence studies. Despite the approximate nature, the accuracy of Type I error rate, statistical power, and sample size calculations of the suggested equivalence test is justified under a wide range of model configurations. The proposed procedures are demonstrated with the data of a clinical trial regarding the comparative study of four antihypertensive treatments. A complete set of computer codes is presented to calculate the corresponding critical values, p-values, power levels, and sample sizes for data analysis and design planning of equivalence studies.