Session 8: Sample Size Determination

This video covers “Sample Size Determination”, the eighth session in the Pediatric Emergency Medicine Fellowship Research Design Course, directed by Dr. Michael Mojica and Dr. Michael Tunik. This session explains how to determine the number of subjects needed for a study to ensure valid, reliable, and ethically sound results.

Topics covered include:
• The relationship between hypothesis testing and sample size determination
• Understanding alpha (Type I) and beta (Type II) errors, power, and effect size
• Distinguishing between superiority, equivalence, and non-inferiority hypotheses
• How to calculate sample size for different data types (means vs. proportions)
• The role of clinically significant differences in defining effect size
• Selecting the correct statistical test based on data type and study design
• Interpreting parametric vs. non-parametric tests and one-tailed vs. two-tailed analyses
• Practical examples using G*Power and SealedEnvelope.com for sample size calculations
• Adjusting assumptions (alpha, beta, variability, effect size) to enhance study power
• Ethical implications of underpowered studies and strategies to improve efficiency

This session provides a practical, step-by-step framework for planning sample size calculations in clinical research, helping investigators ensure their studies are both scientifically valid and ethically justified.

Presented by:
Michael Mojica, M.D. and Michael Tunik, M.D.
Pediatric Emergency Medicine Fellowship, NYU Grossman School of Medicine

Next session: Writing a Research Proposal for the IRB.