Correlation
Find sample size: If you know the correlation coefficient, use this form to find how many subjects you need.	Find correlation coefficient: If you know the number of subjects, use this form to find smallest detectable correlation.
Correlation coefficient (rho): Click here for sample size: You will need subjects	Number of subjects: Click here for rho: You can detect r > or r <
For different power or significance level, change the fields below: Alpha: Prob(reject H0 when H0 is true) 0.05 0.01 0.005 0.001 0.0005 0.0001 Power: Prob(reject H0 when H1 is true) 0.80 0.90
Choose another study design v. 03/03 Contact: sfh2@columbia.edu Source: G.W. Snedecor & W.G. Cochran Statistical Methods (7th ed., p. 104)