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Sample Size Re-estimation Simulator

Afraid your trial might be underpowered? SSR lets you adjust sample size at an interim analysis based on observed trends — using the Promising Zone design. Compare fixed vs adaptive strategies across multiple effect sizes.

1 Trial Parameters
2 Fixed vs SSR Comparison

Power: Fixed vs SSR-Adaptive

Average Sample Size

Futility Stop Rate

Zone Distribution

3 Effect Size Sweep
Effect (delta)Fixed PowerSSR PowerAvg N (SSR)Futility %Zone