My first thought on reading the article's four kinds of aggression, is that the difference among them as to whether or not testosterone is associated with might

My first thought on reading the article's four kinds of aggression, is that the difference among them as to whether or not testosterone is associated with might explain some of the differences that different research(ers) finds. If you're studying different categories, or worse yet lumping them all together, you may miss an important affect, or apply one to categories that it doesn't belong in.