When lab companies create a test they take a bunch of samples from a wide range of people (in the case of testosterone, they sample men and women separately) and come up with a value in the numeric middle that's known as the average. Now without going into too much statistics, the lab also generates a range of values we call the "normal" range. 'Ok, so what?', you might be saying. Well, depending on the lab, the "normal" range for testosterone is somewhere in the vicinity of 300-1200. That's a huge span, four-fold or 300% difference. So why the big deviation? When the lab generates the "normal range", they are testing guys of all different ages: young ones, middle age ones, old ones, and sometimes really old ones. So the age range might be 21-85, which is about the same 300% difference we saw in the lab values. We can assure you the guy with the level of 1100 is feeling and functioning a lot better than the gentleman with a level of 305. This is where the concept of optimal comes in.