Gee, thanks! I think P-value explination is way above my pay grade. (I'm still in the mailroom)
P-values are calculated to show the trial results are significant, and not a result of "chance". The FDA has some excellent statisticians that calculate these numbers (along with many others) for their trials. The FDA usually requires a P value of .05 or below to give a drug approval. There are always exceptions to the rule, but it's not common.
The equations used to calculate these are quite complicated, so I won't even try to explain those. I couldn't calculate one if I had too.
Here's a document that explains them fairly well:
www.haverford.edu/math/lbutler/glossary/p_values.doc
