Usermail: Using ELO for tournaments

"I noticed on ChaosWins that you are using ELO scoring in your 40K tournaments. I am thinking of doing the same for my local store, but I have a few questions for you.

1) What is your starting score for new players?

2) Are you recalculating ELO score between rounds, or just after the tournament?

3) What K factor are you using to get the new ELO scores after the tournament?

4) Are you using the formula 1 / ( 1 + 10 ^ [ Opponent ELO - Player ELO ) / 400 ] ) to calcultate the expected win percentage?

I'll take any help you can give me, even if it's just a spreadsheet.

Thanks,

Ryan Freels"

Good questions here. I thought it would be beneficial to shed light on exactly how we use our ELO system:

For starters I've touched on some of this in this previous article here.

But to answer your questions directly:

1) All players start at the score of 1600
2) I calculate scores in between rounds
3) For our RTT's we do a K factor of 10.
4) Correct. This probability is then used to recalculate each player’s rating after the match. In the equation below, players receive 1 point if they win the match, 0 if they lose, and 0.5 for a draw. Players’ new ratings are determined as follows:

Player’s New Rating = Player’s Old Rating + (K-Value * (Scoring Points–Player’s Win Probability))

For ease of use I just use this handy calculator located here.

K factors are a multiplier for the event. The higher the rating the most heavy the impact the tournament has on a players rating. For RTT's we are using a K factor of 10. If we do a GT in the future? Expect it to be much higher.

So it's pretty straightforward with the calculator. Simply determine player A and B and then adjust their scores accordingly after the round. If you want big gains in your score then beat high rated players, and don't lose to scrubs.

For you TO's out there, I hope that helps. For you players who are interested in a system like this: Show it to your TO's.