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547 results on '"Shkedy, Ziv"'

4. Latent Class Evaluation in Educational Trials: What Percentage of Children Benefits from an Intervention?

Author

Uwimpuhwe, Germaine, Singh, Akansha, Higgins, Steve, Coux, Mickael, Xiao, ZhiMin, Shkedy, Ziv, and Kasim, Adetayo

Abstract

Educational stakeholders are keen to know the magnitude and importance of different interventions. However, the way evidence is communicated to support understanding of the effectiveness of an intervention is controversial. Typically studies in education have used the standardised mean difference as a measure of the impact of interventions. This measure, commonly known as the effect size, is problematic, in terms of how it is interpreted and understood. In this study, we propose a "gain index" as an alternative metric for quantifying and communicating the effectiveness of an intervention. This is estimated as the difference in the percentage of children who make positive gains between the intervention and control groups. Analysis of four randomized controlled trials in education supports the expectation that most children make progress due to normal school activities, which is independent of the intervention. This study elaborates a method to illustrate how trials with a positive gain index and with a higher percentage of pupils with positive gain in the intervention group can be used to communicate which trials are effective in improving educational outcomes.

Published
2022
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9. Evaluation of Surrogate Endpoints

Author

Molenberghs, Geert, primary, Shkedy, Ziv, additional, Tomasz, Burzykowski, additional, Buyse, Marc, additional, Alonso Abad, Ariel, additional, and Van der Elst, Wim, additional

Published
2021
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10. Sustainable Statistical Capacity-Building for Africa: The Biostatistics Case

Author

REDDY, Tarylee, NSUBUGA, Rebecca, Chirwa, Tobias, SHKEDY, Ziv, Mwangi, Ann, AWOKE AYELE, Tadesse, DUCHATEAU, Luc, JANSSEN, Paul, REDDY, Tarylee, NSUBUGA, Rebecca, Chirwa, Tobias, SHKEDY, Ziv, Mwangi, Ann, AWOKE AYELE, Tadesse, DUCHATEAU, Luc, and JANSSEN, Paul

Subjects
Statistics and Probability, education, research, consulting, statistical capacity, human capital, South-North collaboration, Statistics, Probability and Uncertainty
Abstract

Several major global challenges, including climate change and water scarcity, warrant a scientific approach to generating solutions. Developing high quality and robust capacity in (bio)statistics is key to ensuring sound scientific solutions to these challenges, so collaboration between academic and research institutes should be high on university agendas.To strengthen capacity in the developing world, South-North partnerships should be a priority. The ideas and examples of statistical capacity-building presented in this article are the result of several monthly online discussions between a mixed group of authors having international experience and formal links with Hasselt University in Belgium. The discussion focuses on statistical capacity-building through education (teaching), research, and societal impact. We have adopted an example-based approach, and in view of the background of the authors, the examples refer mainly to biostatistical capacity-building. Although many universities worldwide have already initiated university collaborations for development, we hope and believe that our ideas and concrete examples can serve as inspiration to further strengthen South-North partnerships on statistical capacity-building. We are grateful to the reviewer for the in-depth reading of earlier drafts of this article and for many valuable suggestions. We also acknowledge the support of Kristien Verbrugghen (VLIRUOS director) and Tim Zeuwts (VLIR-UOS staff ) and of Lieve Quanten and Stefanie Kerkhofs (both UHasselt)

Published
2023
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13. Estimating infectious disease parameters from data on social contacts and serological status

Author

Goeyvaerts, Nele, Hens, Niel, Ogunjimi, Benson, Aerts, Marc, Shkedy, Ziv, Van Damme, Pierre, and Beutels, Philippe

Subjects
Statistics - Applications
Abstract

In dynamic models of infectious disease transmission, typically various mixing patterns are imposed on the so-called Who-Acquires-Infection-From-Whom matrix (WAIFW). These imposed mixing patterns are based on prior knowledge of age-related social mixing behavior rather than observations. Alternatively, one can assume that transmission rates for infections transmitted predominantly through non-sexual social contacts, are proportional to rates of conversational contact which can be estimated from a contact survey. In general, however, contacts reported in social contact surveys are proxies of those events by which transmission may occur and there may exist age-specific characteristics related to susceptibility and infectiousness which are not captured by the contact rates. Therefore, in this paper, transmission is modeled as the product of two age-specific variables: the age-specific contact rate and an age-specific proportionality factor, which entails an improvement of fit for the seroprevalence of the varicella-zoster virus (VZV) in Belgium. Furthermore, we address the impact on the estimation of the basic reproduction number, using non-parametric bootstrapping to account for different sources of variability and using multi-model inference to deal with model selection uncertainty. The proposed method makes it possible to obtain important information on transmission dynamics that cannot be inferred from approaches traditionally applied hitherto., Comment: 25 pages, 6 figures

Published
2009

21. Modeling the positive testing rate of COVID-19 in South Africa using a semi-parametric smoother for binomial data

Author

OWOKOTOMO, Olajumoke Evangelina, Manda, Samuel, CLEAESEN, Jurgen, KASIM, Adetayo, SENGUPTA, Rudradev, Shome, Rahul, Subhra Paria, Soumya, REDDY, Tarylee, SHKEDY, Ziv, OWOKOTOMO, Olajumoke Evangelina, Manda, Samuel, CLEAESEN, Jurgen, KASIM, Adetayo, SENGUPTA, Rudradev, Shome, Rahul, Subhra Paria, Soumya, REDDY, Tarylee, and SHKEDY, Ziv

Subjects
South Africa, semi-parametric smoothing model, positive testing rate, Public Health, Environmental and Occupational Health, COVID-19, transmission rates
Abstract

Identification and isolation of COVID-19 infected persons plays a significant role in the control of COVID-19 pandemic. A country's COVID-19 positive testing rate is useful in understanding and monitoring the disease transmission and spread for the planning of intervention policy. Using publicly available data collected between March 5th, 2020 and May 31st, 2021, we proposed to estimate both the positive testing rate and its daily rate of change in South Africa with a flexible semi-parametric smoothing model for discrete data. There was a gradual increase in the positive testing rate up to a first peak rate in July, 2020, then a decrease before another peak around mid-December 2020 to mid-January 2021. The proposed semi-parametric smoothing model provides a data driven estimates for both the positive testing rate and its change. We provide an online R dashboard that can be used to estimate the positive rate in any country of interest based on publicly available data. We believe this is a useful tool for both researchers and policymakers for planning intervention and understanding the COVID-19 spread.

Published
2023
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23. Single Contrast Tests

Author

Lin, Dan, Shkedy, Ziv, Yekutieli, Daniel, Burzykowski, Tomasz, Göhlmann, Hinrich W. H., De Bondt, An, Verbeke, Tobias, Bijnens, Luc, Lin, Dan, editor, Shkedy, Ziv, editor, Yekutieli, Daniel, editor, Amaratunga, Dhammika, editor, and Bijnens, Luc, editor

Published
2012
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24. Adjustment for Multiplicity

Author

Yekutieli, Daniel, Lin, Dan, Shkedy, Ziv, Amaratunga, Dhammika, Lin, Dan, editor, Shkedy, Ziv, editor, Yekutieli, Daniel, editor, Amaratunga, Dhammika, editor, and Bijnens, Luc, editor

Published
2012
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25. Model-Based Approaches

Author

Pramana, Setia, Shkedy, Ziv, Göhlmann, Hinrich W. H., Talloen, Willem, De Bondt, An, Straetemans, Roel, Lin, Dan, Pinheiro, José, Lin, Dan, editor, Shkedy, Ziv, editor, Yekutieli, Daniel, editor, Amaratunga, Dhammika, editor, and Bijnens, Luc, editor

Published
2012
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31. Estimation Under Order Restrictions

Author

Shkedy, Ziv, Amaratunga, Dhammika, Aerts, Marc, Lin, Dan, editor, Shkedy, Ziv, editor, Yekutieli, Daniel, editor, Amaratunga, Dhammika, editor, and Bijnens, Luc, editor

Published
2012
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35. The Constraint of Monotonicity

Author

Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, Beutels, Philippe, Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, and Beutels, Philippe

Published
2012
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44. Why This Book? An Introduction

Author

Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, Beutels, Philippe, Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, and Beutels, Philippe

Published
2012
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45. Modeling Multivariate Serological Data

Author

Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, Beutels, Philippe, Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, and Beutels, Philippe

Published
2012
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47. The SIR Model

Author

Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, Beutels, Philippe, Hens, Niel, Shkedy, Ziv, Aerts, Marc, Faes, Christel, Van Damme, Pierre, and Beutels, Philippe

Published
2012
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