After looking at it from all sides, it seems to me that there may be a mistake in the WE calculation on FAQ. Maybe somebody can show me where I am wrong.
Let OR = Opponent's Rating and MR = My Rating.
The WE formula in FAQ is WE = 1/10^((OR - MR/400) +1)
It also gives an example where WE = 0,76 when OR - MR = 200
When I do the calculation, I get 0,32 for this sum. This means that if my rating is 200 HIGHER than my opponent, I am expected to win only one in three games, not three in four! What is my mistake??
I also find that if OR - MR = 0, i.e. when our ratings are the SAME, then the formula calculates a WE of 1/10, or 10%, which seems incorrect, since the intuitive answer must be 50%!
If OR - MR = - 400, then the WE is 1, i.e. I should win all games if my rating is 400 points higher. Sounds OK.
And if OR - MR = 400 (if my opponents rating is 400 points higher than mine) then the WE is 0,01,or 1%, which also makes sense, since even experts can make mistakes!
When the formula is applied in the Rating equation:
NR = OR + k(Sc - WE), then it can be seen that the WE calculation is much more lenient to the loser in a contest when you play someone stronger, than if you lose against a weaker player. I suppose that is to encourage you to play stronger players!
But there is still a problem in my mind. If there is a difference of +100 as against -100 points, the WE is 6% and 18% resp. It is difficult to understand the rationale behind this.
Can an expert perhaps explain this to me??