Also, this is getting to be pretty old software. However, each applet has a help menu, and I do request that you carefully read that before you e-mail me with questions. I need help on using a particular applet I am willing to provide minimal support if you truly don’t understand what inputs are required. There are usually not nice neat formulas. Sample sizes are calculated using root-finding methods in conjunction with power calculations. In a few cases, an approximation is used, and is labeled as such. Typically it is a probability associated with a non-central distribution. What formula(s) do you use in these calculations? In most cases, power is an exact calculation based on the distributional situation in question.