Power analysis for paired group means

If you are evaluating the same people at two different times and comparing a numerical variable in these people, you can estimate the minimum number of participants needed in each group using the expected means and standard deviations you determined from the literature.

Required information

Before application mean and standard deviation;

Mean and standard deviation after application;

Correlation value between the values obtained before and after the application

Sample calculation: : While the mean and standard deviation values obtained from the literature for the pre-application period are 10±5, and the mean and standard deviation obtained after the application period are 8±5, assuming that there will be a correlation of r=0.50 between the pre-application and post-application measurements, the information should be entered into the application as follows to calculate the minimum number of participants required to find a significant difference at the 0.05 level and with 80% power.