Simon Two-Stage Design Calculator

Input Parameters

This calculator helps determine optimal or minimax two-stage designs for phase II clinical trials, allowing early termination for futility.

Minimum Stage 1 Sample Size: Value between 1 and 500

Maximum Stage 1 Sample Size: Value between 1 and 500

Maximum Total Sample Size: Value between 2 and 500

Probability under the null hypothesis (p₀): Value between 0 and 1

Probability under the alternative hypothesis (p₁): Value between 0 and 1

Maximum Alpha: Type I error rate

Minimum Power (1 - β): Value between 0 and 1

Enroll N1 patients in Stage 1
Count the number of responses (x1) in Stage 1
If x1 ≤ n1, stop the trial and conclude the treatment is ineffective
If x1 > n1, continue to Stage 2 and enroll an additional (N - N1) patients
Count the total number of responses (x) across both stages
If x > n2, conclude the treatment is effective; otherwise, conclude it is ineffective

Design Types:

Minimax Design: Minimizes the maximum possible sample size needed
Optimal Design: Minimizes the expected sample size under the null hypothesis