Sample size determination for clinical research

Area of Science:

• Biostatistics
• Clinical Trial Design
• Research Methodology

Background:

• Statistical power is a critical determinant of a study's validity.
• Inadequate statistical power, except in safety and feasibility studies, renders research unethical.
• Sample size calculation is inherently imprecise, necessitating careful consideration of assumptions.

Purpose of the Study:

• To emphasize the importance of accurate sample size calculation in research.
• To highlight the ethical implications of inadequate statistical power.
• To guide researchers in making realistic assumptions for sample size determination.

Main Methods:

• Review of principles in statistical power and sample size calculation.
• Discussion on the impact of dropouts on study power.
• Emphasis on the necessity of planning for interim analyses to adjust sample size.

Main Results:

• Sample size calculation is not an exact science.
• Realistic and well-researched assumptions are vital for appropriate sample size.
• Accounting for dropouts and planning interim analyses are key components of robust sample size determination.

Conclusions:

• Accurate sample size calculation is fundamental for ensuring adequate statistical power.
• Ethical research requires sufficient power, making sample size a critical consideration.
• Researchers must employ realistic assumptions and adaptive strategies like dropout accounting and interim analyses for valid study outcomes.