What statistical contributions does the Biostatistician make during the trial design phase?

Conducting sample size calculations and writing the statistical analysis plan.

The Biostatistician, or Medical Statistician, provides crucial methodological and statistical expertise applied across the entire lifespan of the trial, with significant input right at the beginning. During the trial design phase, their specialized knowledge is essential for determining the appropriate scale of the study. This involves performing complex sample size calculations to ensure the trial has adequate statistical power to detect a meaningful effect, if one exists. They are also responsible for formulating the precise roadmap for how data will be interpreted by writing the statistical analysis plan (SAP). This SAP is often incorporated directly into the trial protocol document, guiding all subsequent analytical procedures, which the Biostatistician later executes during interim and final data analyses.