Correlation Study Sample Size

30%

r = 0.30

80%

Results will appear here

Enter the expected correlation coefficient and study parameters to calculate the required sample size.

Formula

Sample Size for Correlation Studies

n=(Zα/2+ZβC(r))2+3n = \left(\frac{Z_{\alpha/2} + Z_{\beta}}{C(r)}\right)^2 + 3

Where:

C(r)=12ln⁡(1+r1−r)C(r) = \frac{1}{2}\ln\left(\frac{1+r}{1-r}\right)
  • n = required sample size
  • r = expected correlation coefficient
  • C(r)C(r) = Fisher's z-transformation
  • Zα/2Z_{\alpha/2} = Z-score for significance level
  • ZβZ_{\beta} = Z-score for power