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2x2 Crossover Design Sample Size Calculator

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Calculate the sample size for a two-period, two-treatment crossover trial where each subject receives both treatments.

Study Parameters
Results

Required Sample Size

64

Group 1: 32 | Group 2: 32

Achieved Power

80.7%

Effect Size

0.500

Method: Two-sided 2x2 crossover design
Total subjects64
Per sequence (AB, BA)32
delta / sigma_w0.500
  • •Two-period, two-treatment crossover design
  • •No carryover effect (or adequate washout period)
  • •No period effect (or adequately modelled)
  • •Normally distributed within-subject differences
  • •Two-sided hypothesis test
Formula
n = (z_{alpha/2} + z_beta)^2 * 2 * sigma_w^2 / delta^2
References
  1. Senn S (2002). Cross-over Trials in Clinical Research, 2nd ed. Wiley.
  2. Jones B, Kenward MG (2015). Design and Analysis of Cross-Over Trials, 3rd ed. CRC Press.