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Rao-Blackwellizing field goal percentage
| Content Provider | Scilit |
|---|---|
| Author | Daly-Grafstein, Daniel Bornn, Luke |
| Copyright Year | 2019 |
| Abstract | Shooting skill in the NBA is typically measured by field goal percentage (FG%) – the number of makes out of the total number of shots. Even more advanced metrics like true shooting percentage are calculated by counting each player’s 2-point, 3-point, and free throw makes and misses, ignoring the spatiotemporal data now available (Kubatko et al. 2007). In this paper we aim to better characterize player shooting skill by introducing a new estimator based on post-shot release shot-make probabilities. Via the Rao-Blackwell theorem, we propose a shot-make probability model that conditions probability estimates on shot trajectory information, thereby reducing the variance of the new estimator relative to standard FG%. We obtain shooting information by using optical tracking data to estimate three factors for each shot: entry angle, shot depth, and left-right accuracy. Next we use these factors to model shot-make probabilities for all shots in the 2014–2015 season, and use these probabilities to produce a Rao-Blackwellized FG% estimator (RB-FG%) for each player. We demonstrate that RB-FG% is better than raw FG% at predicting 3-point shooting and true-shooting percentages. Overall, we find that conditioning shot-make probabilities on spatial trajectory information stabilizes inference of FG%, creating the potential to estimate shooting statistics earlier in a season than was previously possible. |
| Related Links | http://arxiv.org/pdf/1808.04871 http://www.degruyter.com/downloadpdf/j/jqas.ahead-of-print/jqas-2018-0064/jqas-2018-0064.xml |
| Ending Page | 95 |
| Page Count | 11 |
| Starting Page | 85 |
| ISSN | 21946388 |
| e-ISSN | 15590410 |
| DOI | 10.1515/jqas-2018-0064 |
| Journal | Journal of Quantitative Analysis in Sports |
| Issue Number | 2 |
| Volume Number | 15 |
| Language | English |
| Publisher | Walter de Gruyter GmbH |
| Publisher Date | 2019-06-26 |
| Access Restriction | Open |
| Subject Keyword | Journal of Quantitative Analysis in Sports Robotics Basketball Bayesian Regression Optical Tracking Shot Trajectories Variance Reduction Journal: Journal of Quantitative Analysis in Sports, Vol- 15 |
| Content Type | Text |
| Resource Type | Article |
| Subject | 3300/3301 1800/1801 |
