Thursday, February 19, 2009

Chuck Rey on "In Play Efficiency"

Chuck Rey, volunteer assistant coach at the University of Minnesota, e-mailed me this morning with a statistical variation on hitting percentage.

Rather than putting the emphasis on kills, which the usual measure of hitting percentage does, the Gophers focus on putting the ball in play (i.e., getting a kill or at least not spiking the ball out of bounds or into the net). They even have a name for it, the "In Play Efficiency" or IPE. As Chuck stated in his e-mail to me, the "IPE stat is just a 1 - the error %."

In addition to the Hitting IPE, there's also "Total IPE," where the error rate is based on "all team errors commited (blocks errors, hitting errors, service errors, ball handling errors, passing errors)."

Chuck was kind enough to present me with season-long IPE statistics for the Final Four NCAA women's teams from last December, which I am posting with his permission.

Chuck also has his own website at .


Mark said...

That all looks great, but what does it mean, or what is it supposed to mean?

Chuck Rey said...

Its putting a positive spin on hitting errors. Many coaches tell players, "Don't make hitting errors", focusing on the negative. When using IPE with a goal of .900, a player is able to recognize they need to keep 9 out of 10 attacks in play. A focus on the positive. An attainable outcome goal a player can work towards.

Mark said...

A couple of things...
I've never heard before that errors alone was a predictor/determinant of success. Do you have some research on this?
Secondly, how do you balance the positive nature of the feedback towards errors, with fact that the statistic disregards attack kills which seems counterintuitive to me.

Chuck Rey said...

There is no one stat, or any stat for that matter, that is a predictor or determinant of success. Stats are used to provide trends of players and teams as a guide of strengths and weaknesses. The IPE stat is one stat of many that breaks down hitting percentage. Hitting percentage is a combination of error % and kill %. Both parts are essential to a hitter and a team's success. For example, the average hitting IPE of the four final four teams was .875. This number can become a team goal to strive for. In addition to this goal, the average kill percentage of the final four teams was 0.455, with one team far exceeding this average of 0.529 - care to guess which team?

So it is a combination of IPE and kill % that can be used as a guide for players and teams to measure their level of success versus the competition. If a team has an IPE of 0.875 or a goal of 9 attacks out of 10 attempts hit in play, PLUS has a kill % of .455 or 5 balls out of 10 attacks as kills, the team has a great chance for success.

Again, this is just one category and set of statistics of many that needs to be reviewed to gauge a team's progress.