Module 4

Inputs to Analysis, Recruitment Feasibility, and Multiple Aims

Our emphasis in the fourth module includes the many sources of inputs for power and sample size analysis from the empirical literature, internal pilot studies, planned pilot studies, and computer simulations. Each of these approaches is discussed in detail in relation to power and sample size analysis, including the overall benefits and challenges associated with each approach. Next, we talk about recruitment feasibility and its critical importance to sample size calculations by discussing some key factors such as health, socioeconomic, and demographic factors that can be predictive of recruitment difficulty. Next, we deal with research studies that address multiple aims (e.g., hypotheses) and how to address this situation in your sample size analysis. Lastly, you will walk through a fully independent exercise problem to solve for sample size analysis for a multilevel study with longitudinal repeated measures.

Key Concepts

  • Identify the inputs for power or sample size analysis, and describe how to search the literature for inputs.
  • Define and describe internal pilot studies, and their benefits and limitations.
  • Describe a planned pilot study, and their benefits and risks.
  • Compare and contrast the difference between planned pilot studies and internal pilot studies.
  • Describe how to simulate power, how long the process takes, and why they can be wrong.
  • Describe enrollment feasibility and its importance in a sample size calculation.
  • Describe multiple aims, the challenges that arise from them, and how to plan for them.
  • Demonstrate how to design a study with multiple aims.


Module Four Activities