PPT-Planning Sample Size for Randomized Evaluations

Jed Friedman World Bank SIEF Regional Impact Evaluation Workshop Beijing China July 2009 Adapted from slides by Esther Duflo JPAL Planning Sample Size for Randomized Evaluations General question . Study Design and Sample Size. Ideally we are involved in a study from the beginning. As statisticians (an epidemiologist) part of our role is to ensure the study is designed to address the primary hypothesis under consideration. Presented by :Dr. . Reshma.S. . Moderator : Dr. . Subodh. S Gupta. Why do we need sample size calculation?. When should we calculate sample size?. Basic principles for sample size calculation. Derivation of sample size formula. Excel. GrowingKnowing.com © 2011. 1. GrowingKnowing.com © 2011. Sample size. How big should a sample be for a valid study?. Why phone 10,000 students if phoning 50 is enough?. Large samples take longer and cost more. Neighborhood. Hill Climbing. : Sample p points randomly in the neighborhood of the currently best . solution; determine the best solution of the n sampled points. If it is better than the . current solution, make it the new current solution and continue the search; otherwise, . Manual. GrowingKnowing.com © 2011. 1. GrowingKnowing.com © 2011. Sample size. How big should a sample be for a valid study?. Why phone 10,000 students if phoning 50 is enough?. Large samples take longer and cost more. November 17, . 2015. Allen Kunselman, MA. Division of Biostatistics and Bioinformatics. Department of Public . H. ealth Sciences. Quotes. An approximate answer to the right question is worth a good deal more than an exact answer to the wrong question.. . Jenny C. Aker. Tufts University. What affects the sample size?. Effect Size. Variance. Sample. Size. Significance. Level. Power. Proportion in. Treatment. Variance in outcome Y. . Jenny C. Aker. Tufts University. What affects the sample size?. Effect Size. Variance. Sample. Size. Significance. Level. Power. Proportion in. Treatment. Variance in outcome Y. 1. GrowingKnowing.com © 2011. Sample size. How big should a sample be for a valid study?. Why phone 10,000 students if phoning 50 is enough?. Large samples take longer and cost more. What if a sample of 50 is not enough, you need 51 for a valid study?. Review of Type I & Type II Errors. When we conduct a test of any hypothesis regardless of the test used we make one of two possible decisions:. Reject the null (H. o. ) in favor of the alternative (H. Alternative Study Designs and Randomization Schemes. Demonstrated on . Paul Murphy. nQuery Research Statistician. Webinar host. Host. AGENDA. 1) . Background. 2) Crossover Trials. 3) Cluster Randomized Trials. Design and Endpoint Considerations. Demonstrated on . Head of Statistics. nQuery. Lead Researcher. FDA Guest Speaker. Guest Lecturer. Webinar Host. HOSTED BY: . Ronan Fitzpatrick. AGENDA. Introduction to Non-inferiority Testing. Wendy . Parulekar. MD, FRCP(C). Wei Tu PhD. Objectives. To review the classification of randomized phase II trial designs. To propose and critique potential  randomized phase II trials designs for a concept in head and neck cancer (case scenario to be presented). Binary, Ordinal and . Contingency Table Data. Ronan Fitzpatrick. Lead Statistician. nQuery. Webinar. Host. Agenda. Categorical Data Overview. Binary Data Methods & Sample Size. Ordinal Data Methods & Sample Size.