The Hidden Forest

Ive been really curious as to how the game figures out if my tradeskill goes up when I try to combine. Anyone who's tried to get their skill to 300 has noticed that sometimes you get a couple points right in a row, other times you don't even see 1. Is it random, does it base off your WIS or INT, your level, or your race? Is there a mathmatical formula it's goin off of?

Making a long formula short this is pretty much how it goes:

Depending on your skill in the tradeskill:
0 - 15: 100% chance to increase
16 - 174: Starts dropping from 92% and evening out at 13%. So at Skill level 16 you have 92% chance, at skill level 174 you have 13% chance.
175+: Starts at 12.5% and evens out at 2.5% chance at skill level 300. So at Skill level 175 you have 12.5% and skill level 300 you have 2.5% chance.

There are of course a lot of extra factors, but that is ultimately how it pans out. Also note that a successful combine has a higher chance of doing a skill up than a failed combine.

Plus the math is crazy. Been going over all the math in all parts of the source the last few months and its really really silly. Like I kick puppies because I'm a deranged lunatic, type of crazy. At least in tradeskills it works as intended.
Just a sidenote.