Rating Estimator

Running Chess Tournaments
1

I received a rating question from one of my recent scholastic tournaments.
The players involved are a brother and a sister; Nice kids, nice family.

Sister: Pre-rating 1203; Score 4-1; Average rating of opponents 981; post rating gain 24 points

Brother: Pre-rating 1171; Score 4-1; Average rating of opponents 903; post rating gain 1 point

Sister’s gain of 24 points seems about right. Brother’s rating gain of one point seems low to me. Sister’s opponents averaged 78 points higher than brother’s but she also was rated 32 points higher than her brother.

I’m fuzzy on the current rating formula these days. Does anyone have a “rating estimator” that I could plug these results into to see if the post rating gains are reasonable? I use to be able to fairly accurately estimate new ratings with the old rating formula; I have trouble doing this with the new rating formula.

2

uschess.org/ratings/calculator.html

– Hal Terrie

3

You can’t just use averages of 5 opponents ratings.

What if he lost to a 1300, and beat 4 800’s? With an 1171 rating, that would probably be about right to have no change.

4

The ratings estimator is also accessible from the left menu area of the new website, under ‘ratings’.

I sympathize with regards to the difficulty in estimating post-event ratings, the formulas (see the link on the ratings page of the old website) are not light reading and it is VERY DIFFICULT to compute them by hand. (I wrote an Excel spreadsheet to do it for a quad during the development of the new ratings programming in early 2005, that task alone took me 4-5 hours.)

5

Thanks to All!