Section outline

    • Selecting the correct number of study participants to test the study hypotheses is a critical step in designing clinical studies. This module presents a concise, step by step approach to selecting sample size and how variations in sample size can influence study outcomes. This module also reviews how to evaluate  power calculations in the medical literature and highlights common errors in the interpretation of P values and power calculations in the published clinical studies. 

    • objective Objectives

    • After completing this module, students should be able to:

      • List the steps for estimating sample size for an analytic study.
      • Explain other considerations in calculating sample size for analytic studies.
      • List the steps for estimating sample size for descriptive studies.
      • Identify strategies to minimize the required sample size.
      • Explain other strategies for estimating sample size when there is insufficient information.

    • Readings Reading

    • In Designing Clinical Research, 4th Edition, by Hulley et al.

      • Chapter 5, Getting Ready to Estimate Sample Size
      • Chapter 6, Estimating Sample Size and Power

    • Optional reading: Sample size conventions: Flaws, harms, and alternatives File
      Not available unless: You belong to Registered Student Only
    • Sample Size Calculator URL
    • Sample Size Calculator Options URL

    • Lecture Lecture

    • Sample Size and Power Slides File

    • Small Group Sections

    • Small group sections for this module take place on Monday and Wednesday during the third week (see section roster for your assigned time and Zoom link).

      Note that this topic and the "Statistics" topic are usually addressed together, as both topics inform each other.

    • Assignments Assignments

    • SAMPLE SIZE AND POWER ASSIGNMENT - Due by Thursday before 5 PM in the third week (email to small group leader) Forum
      Students must
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    • Exercises Optional Exercises

    • Optional Exercises -- Sample Size and Power Quiz
      Not available unless: You belong to Registered Student Only