Your question is Sample Size for Low-Frequency Events. Take a moment with it on the right.
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How do you determine the required sample size and statistical power for an experiment when working with low-frequency biomedical events?
Explain how you would define the estimand, select a clinically meaningful minimum detectable effect, calculate sample size, and account for attrition or unequal allocation. Describe the statistical test, assumptions, analysis timing, and safety guardrails you would pre-register. State how your recommendation changes when the event is extremely rare or the available sample is limited.