Population size = 100

Controlled group = 1 group

Treatment group = 2 groups

Power = 0.8

Alpha = 0.05

Group allocation ratio: All groups have the same sample size

standard deviation of data: 0.25 (assume)

standard deviation of means: 0.15 (assume)

I have tried to use software (PASS: http://www.ncss.com/) to determine the appropriate sample size. I chose One-way ANOVA F-test from the menu and input the above parameters. I got the following results

Numeric Results

Power n G N std of mean(σm) std (σ) effect size Alpha

0.8004 10.00 3 30 0.15 0.25 0.6000 0.0500

My question is how this 10 sample size per group is calculated. Getting result is good , but it would be better if i can get explanations.

Thank you in advance