How to rate Women - Facemash Style

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For those of you that have seen The Social Network you will be familiar with the "Window" Algorithm, also known as the ELU algorithm. It was used by Chess companies, and still is by some, to rate chess players. It is very simple once you understand it. Basically it does this:

1. Calculates chance either candidate has of winning.
   
2. Winner's base rating goes up, losers goes down.
   

What's interesting is the method used to bring the base rating up or down. It is proportional. If somebody with a high probability beats somebody with a low probability (Going with the odds) The values only change a little. If it is the other way round, the values take a huge leap. This will be better demonstrated later.

The first thing you need to do is calculate the probability of each winning.



Both will give the percentage of a and b winning, respectively. Now, we need two things to compare, and we need to give them a base rating (Ra and Rb). So I've decided we should bring out a long fight for this one. Pack3t vs Sharn. Can I hear the crowd roar?


Given these base ratings lets calculate the chance of each winning



So we know who we'd pick to win in a competition based on those base ratings, but what happens if for some reason, Sharn Won!?!? The Base ratings would have to change. Look at what they would become.. (Note: T+1 means Time+1, it essentially means, what Ra/b will become)


But what if, as expected, Pack3t Won?

As you can see, the values don't move anywhere near as much as they did when Sharn won, this means that the equation accounts for the fact that somebody high up, beating somebody low down shouldn't give them as many points. I hope this guide has been useful, if you have any more questions about this equation. Ask, and I will answer to the best of my knowledge.