Sunday, May 19, 2013

USTA Dynamic NTRP Accuracy Part 2

I wrote yesterday on the accuracy of my Estimated Dynamic NTRP Ratings using matches played in the first round of the Northern California Sectionals.  The ratings went 8-2 predicting winners, so let's move on to round 2 and see how they fared.

In one team match, there were the following results:

  • A 4.55 beat a 4.67 6-3, 6-0 - Big miss on this prediction, but see below
  • Court 2 singles was a default
  • A 4.40/4.69 beat a 4.30/4.37 6-2, 6-4 - Pretty much as predicted
  • A 4.63/4.52 beat a 4.49/4.51 6-3, 6-2 - A little more convincing than expected but close
  • A 4.61/4.43 beat a 4.04/4.24 6-3, 6-2 - As expected
So here the ratings went 3-1, again not bad.  Note that in the first match, I'm told the losing player had an elbow injury in the first set and played the second set with his off hand which would explain a lot.  Based on this I'd be inclined to throw this match out and consider the record 3-0.


The other team match had:
  • A 5.0.5 beat a 4.77 6-2, 6-2 - Predicted correct
  • A 4.66 beat a 4.51 6-4, 2-6, 1-0 - Also correct, albeit the loser won more games
  • A 4.61/4.37 beat a 4.81/4.15 6-3, 4-6, 1-0 - Close as expected but correct
  • A 4.49/3.99 beat a 4.36/4.33 7-5, 6-2 - An upset, but the 3.99 is underrated
  • A 4.52/4.47 beat a 4.61/4.57 4-6, 6-4, 1-0 - Another upset, but close
The ratings didn't fare quite as well here going 3-2.


So, a total of 6-2 for this round, or 14-4 overall.  Again, not too bad.  There will always be some variance in play and results based on how players match-up, so predictions like this will never be perfect, but 78% correct certainly isn't bad.