Saturday, January 25, 2014

USTA League NTRP Benchmark calculations and why playoff results carry more weight

2013 USTA League year-end NTRP ratings came out nearly 2 months ago now and 2014 leagues have started in many areas, but I'm still getting questions about 2013 year-end ratings and specifically how playoff results get counted.  So here is a quick summary.

Dynamic NTRP ratings are calculated throughout the year as each match is played.  At year-end though, the final dynamic rating doesn't necessarily become the year-end rating, rather some additional calculations are done.  For one, in sections where tournaments are included in year-end ratings, they get included, but for purposes of this post, there are additional calculations done with playoff results, specifically what are called benchmark calculations.

To understand why there are benchmark calculations, it is important to remember the purpose of the NTRP system.  The main purpose is to rate players at appropriate levels to promote competitive play.  In leagues that advance to Sectionals and Nationals, players from different areas that likely have no history of playing each other come together to play which can make ensuring competitive play occurs difficult.  How can we expect that a 4.0 from Miami is of generally the same playing ability as a 4.0 from Seattle?  The answer is benchmark calculations.

The USTA does not publish details on how benchmark calculations are specifically done, but what follows is a high level understanding I've been able to glean from various sources.

When Nationals are complete, the results for each player that played there are given extra weight to calculate their ratings.  This is done to try to get the ratings of the Nationals players from each section to be accurate relative to each other.  Then using the ratings of the Nationals players, this is done at the section level to have how weak or strong the section's representative was at Nationals filter back in to the section.  This then gets repeated at the early stages of players, e.g. Districts, Regional, and Local, to continue to have the ratings be adjusted so that a 4.0 (and every other NTRP level) in New York City is relatively the same as in Iowa.

Make sense?  As you can imagine, doing all these calculations are not trivial, which is why it is roughly a month between when Nationals finish and the year-end ratings are published.

Hopefully this helps answer the question.  Leave a comment if you have more.