heres the definition for you.
In poker, the Independent Chip Model (ICM) is a mathematical model used to calculate a player's overall equity in a tournament. The model uses stack sizes alone to determine how often a player will finish in each position (1st, 2nd, etc.).
using your chip count to decide the payout split, so i would only agree to this kind of split if all stacke were pretty close to the same size, if there was one person or two people with a much shorter stack size i would offer them a smaller part. and if i was the smaller stack size i would not take this deal, cause you very well might be able to come back and be a chip leader.
Ive had people in live games want to split equally when we were down to just a few players, and i would say no to that and offer a smaller cut to the smaller stacks, but they were generally decline. or i would take the split if the jump in payout wasnt much of a jump sometimes its just a matter of a 100 to a few hundred then might as well because its just not worh the time.
hope this helped gl and nice job