That's why he analyzes them by observing their online interactions. There are things they talk about over and over. Loper distinguishes hacking from computer crime with a subset in-between that he calls criminal hacking, which would include network intrusion. If they fall into the hacker mold, they probably won't cause trouble. If not, they are probably a computer criminal.
Hackers also have a social network.
Computer criminals don't hang out like hackers. And, Loper says, there's more to learn about hackers. The literature is much better on computer criminals, he notes. Loper's interactions with hackers have been a boon to his research. A hacker even helped him create the program to analyze the data for his dissertation.