I wrote it. I haven't had _any_ statistics courses -- my knowledge of statistics comes from one o' those test prep books (Schaum?) which I bought when, back in the dark ages, I had to figure out and fix, real fast, a 9000-line Fortran program that did statistical analysis of the behavior of communications channels. Knowing nothing about statistics, I figured I should at least be able to parrot the vocabulary to myself. (This method worked.) However, it seems to me that the variable in question is one of the sorts of things that tend to fall into a bell-curve pattern. I could probably perform a rationalization of this belief if it would entertain anyone.
I did say it was a dumb question; see above. I haven't understood the answers, by the way. I haven't achieved a clear view of the mechanism which holds wages up, given the difference of power between the classes.