I have been using NCSS in my high school class room for 22 years. I find it very easy to use and my students use it to calculate their results for their lab reports, science fair projects, and now they are using it for AP Research projects. It can be used for everything from the basics to the most advanced statistics. NCSS is very affordable for any high school budget.
NCSS is an excellent tool for clinical and epidemiological research that is both user friendly and economical with excellent support. It removes the "fear of statistics" from clinical research and makes research accessible to all curious clinicians.