One-sample t-test
Find sample size: If you can estimate group mean and standard deviation, use this form to find the number of subjects you need. Group mean: Comparison value: Standard deviation: Click here for sample size: You will need subjects	Find effect size: If you know the number of subjects and the standard deviation of your measurement, use this form to see what mean values will be significant. Number of subjects: Standard deviation: Comparison value: Click here for effect size: You can show significance with a mean > or a mean <
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)