Isn't there something also about the skill level (probably PRW) of the player who is killing verses the player who is killed? For example, if a really good player kills a noob, the change in the rating is minimal, whereas the noob killing the good player, the calculation favors this more?
I've noticed that in the spree stats for each map, there is rating variance and things like that that are stored. I'm assuming this data is used in the calculation somewhere, which may explain why some people complain that KR is so weird on some servers and doesn't make sense?
Yes, ETPub's KR takes skill of killed player into account. Making "easy kills" on noobs won't improve your KR much, but killing a much better player than you will improve your KR much more.
KR is independent of PRW, and doesn't really make sense in a multiplayer game since it takes into account only the attacker and the victim, much like an independent 1vs1 game. But PRW is quite interesting imho. PRW also (optionally) takes the difficulty of the map into account.
If you're interested in knowing more, look for J.Menke's documentation: "A Bradley-Terry Artificial Neural Network Model for Individual
Ratings in Group Competitions", and "Hierarchical Models for Estimating Individual Ratings from Group Competitions" (the later being an updated version). Strong background in mathematics/statistics recommended.
Edited by Spyhawk, 07 January 2014 - 05:36 PM.