"Cross-regional studies of medical practice variations and comparisons of individual physicians' "styles" show considerable differences between the rates of use of medical care across providers. Presuming (for the moment) that the populations being treated in these comparisons are equivalent (or sufficiently so to ignore the differences), would you say that these studies show (a) that some doctors treat too much; (b) some doctors don't treat enough; (c) both; (d) neither; or (e) we can't tell from data such as that? Explain your conclusion."