Pseudo Crit (need help)

Summoners, Has anyone done any research on how critical chance work. Because i know that they have some kind of algorithim that makes crits less random. (to make the game kinda fair). I have already done a simple experiment where I tested 50% crit chance. and it turned out that out of 500 auto attacks I was bound to crit within 4 hits. I am aware that dota II has a similar system to deal with randomness.

The reason why i need some type of reference is because im planing to have this as a math project where i analyze the crit chance. However in order for me to do this as a school project i need some kind of reference to another source. It doesnt have to be any fancy research or anything but it has to be something.

tl:dr can someone link research to pseudo crit chance in lol.