Reworking the Four Factors to highlight shot selection
Posted: Thu Feb 21, 2013 1:47 pm
Not sure if people have seen it, but earlier this year I built a metric for evaluating shot-selection. I've been calling it Expected Points Per Shot (XPPS), and it's built around expected point values for shots from different locations. It's a variation on TS% and the formula boils down to (Expected Points/True Shot Attempts). I've been tracking these numbers all season long for players and teams (teams I have both offensively and defensively). Here are links to the Tableau Visualizations - http://www.hickory-high.com/?page_id=6154
At the suggestion of DSMok1 I did some regression analysis to see how my XPPS numbers related to TS% and ORTG. With plenty of help from him I was able to pull the whole project through. We arrived at these figures. 24.1% of the variation in TS% can be explained by variation in shot selection (as expressed by XPPS), and 19.1% of the variation in a team's ORTG can be explained by the variation in shot selection (as expressed by XPPS). Here's a link to the whole analysis: http://www.hickory-high.com/?p=6259
The crux of the analysis was the revelation that you could explain ORTG just as well as the Four Factors do by using just TS%, ORB% and TO%. Since TS% can be explained entirely by XPPS and Shot-Making Difference (the difference between PPS and XPPS) we can simply replace TS% with those two elements in the regression equation. So essentially we reworked the Four Factors, obscuring shooting accuracy slightly, or at least presenting it in a different format than we're used to seeing it, and instead highlighted shot selection.
Would love thoughts, feedback and constructive criticism!
At the suggestion of DSMok1 I did some regression analysis to see how my XPPS numbers related to TS% and ORTG. With plenty of help from him I was able to pull the whole project through. We arrived at these figures. 24.1% of the variation in TS% can be explained by variation in shot selection (as expressed by XPPS), and 19.1% of the variation in a team's ORTG can be explained by the variation in shot selection (as expressed by XPPS). Here's a link to the whole analysis: http://www.hickory-high.com/?p=6259
The crux of the analysis was the revelation that you could explain ORTG just as well as the Four Factors do by using just TS%, ORB% and TO%. Since TS% can be explained entirely by XPPS and Shot-Making Difference (the difference between PPS and XPPS) we can simply replace TS% with those two elements in the regression equation. So essentially we reworked the Four Factors, obscuring shooting accuracy slightly, or at least presenting it in a different format than we're used to seeing it, and instead highlighted shot selection.
Would love thoughts, feedback and constructive criticism!