« Since I'm Sure You're Waiting with Bated Breath | Main | Oh, Snap! »
November 15, 2006
John Hollinger: Master Statistician
ESPN's resident statistician wants to see if he can make any interesting claims about the affect of the new ball on the game. Here's what he comes up with:
The most interesting data, however, come when the ball gets a little closer to the rim. Let's start from the foul line, where the league has improved from 73.3 percent to 74.5 percent. This is an impressive jump considering the league leader in free-throw attempts, LeBron James, has been notably inaccurate from the stripe.[...]
This is the most compelling evidence to date that the ball does tend to offer a kinder bounce to shooters. That said, let's be realistic about the scope of the difference: We're talking about one free throw out of 100.
So, you're calling that 1.2 percent change "an impressive jump," and "compelling," while also pointing out that it's not significant? What are we supposed to think? Also, what is the variance in "free throw percentage in November" like, year-to-year? I'm guessing it's way more than 1%, which means that you can't make any interesting claims at all about the difference between this year and last, much less any claims about the relationship between the new ball and scoring totals.
(In case you're wondering: yes, I am just bitter that I can't get Insider content.)
Posted by todd at November 15, 2006 11:23 PM
Comments
Todd,
First, buy a subscription to ESPN The Mag. Various website sell the magazine for less that $5 for a one year subscription and it comes with Insider free. That’s what I did. I must take issue with your opinion concerning Hollinger’s piece. I will point out that I believe Hollinger picked up the wrong numbers for his column. See (http://blog.stats.com/2006/11/ballgate.html).
1. To say “We’re talking about one free throw out of 100” does not mean that a 1+ percentage point increase is not significant. Hollinger I believe means to indicate that the change isn’t dramatic or overtly perceptible.
2. Taking the YTD percentage from the above website gives you a free throw percentage of 76.1. That compares to a mean for the previous 8 seasons of 74.9 and standard deviation of .0087. That means 76.1 is statistically significant at almost 1.5 std devs from the mean. And, as you can see 76.1 is also a higher percentage than has been recorded for any decade going back to the seventies.
Posted by: Jeff at November 22, 2006 11:15 PM
Post a comment
Thanks for signing in, . Now you can comment. (sign out)
(If you haven't left a comment here before, you may need to be approved by the site owner before your comment will appear. Until then, it won't appear on the entry. Thanks for waiting.)