One thing I’ve noticed is that experienced fighters tend to fall into one of two groups.
Group #1 is made up of experienced fighters who don’t have much of an ego anymore (with respect to fighting) and don’t feel they have anything to prove anymore. They know they’re tough (based on much experience). They don’t start fights. The let a lot of things “slide”. They’ll fight if provoked, but won’t start it.
Group #2 is made up of what I’ll call “hot heads” who like starting fights with others.
Although a tournament to determine the targets’ actual fighting ability would be neither ethical nor practical, we do know the number of fights target males reported to have had during the last 4 years (electronic supplementary material). If more formidable men are more likely to initiate fights or less likely to avoid them (because they are more likely to win), then the number of fights a man has been in would be a rough index of his actual formidability. Indeed, men who were seen as tougher had been in more fights: there was a correlation of r=0.30 (p=0.02) between average toughness scores and the targets’ actual fighting behaviour. This means that perceptions of a man’s fighting ability track a real world behaviour that is a plausible index of his actual formidability.
My experience is that the toughest guys tend not to get in fights very often (unless it is somehow part of their job). The reason is that most people wouldn’t dare get in a fight with them.
If you’ve seen guys of this toughness class, you’ll notice people (who don’t know them) will avert their gaze if the toughest guys makes eye contact with them. Many people will move out of their way.
Now the toughest guys do get into fights from time to time. But, based on my experience, I’d imagine it’s a lot less than others a little below their toughness class.
Thus I don’t think it is a good idea to use the number of fights a person has had “during the last 4 years” as a proxy for toughness.
Although testing fighting ability directly wold be a much better, if you want to look at a person’s fighting history, at least, only count the fights they didn’t loose (or weigh the fights they lost less). Or better, don’t restrict it to the last 4 years, but count all the fights they’ve had throughout their whole life. (That way if the fighter is now in “group #1″ mention at the beginning of this article, you still capture them too.)