Just how bad was the free throw discrepancy in Game 2?

An inquisitive reader asked me to examine just how bad was the home/away free throw attempt discrepancy in game 2. Using regular season data from 1986-2008, I calculated home fta – away fta, finding a maximum of 41 (on 02/06/93 DEN v DAL) and a minimum of -41 (on 11/19/03 NYK v LAL). The mean discrepancy in favor of the home team is 1.364, and the standard deviation is 10.254. Below is a plot of the empirical density, with Game 2 indicated with a red line:

Game 2’s difference, 38-10=28, is 2.598 standard deviations above the mean. If my counting is correct, this puts the game in the 0.994 percentile of games in terms of pro-home free throw attempt discrepancy. What I cannot tell you, unfortunately, is whether it was the officiating, or the play, that lead to the difference.

5 responses to “Just how bad was the free throw discrepancy in Game 2?

  1. This relates to a simulation program I’m building: how does shot selection affect the probability of being fouled?

    If I instruct my team to attack the rim, I’m surely to get to the line more often than if I hang back and shoot mid-range jumpers.

    Sorry for rambling on a little, but ultimately this is how we should look at this problem. I noticed Powe running to the rim a lot, so is Jackson just upset or does he have merit? Was Kobe & Co. running to the rim at the same rate?

    At some point I’ll try and sift through play by play and possibly shot location information to understand this better, but if you (or anyone else out there) has ideas on how the strategy can affect getting to the line, I’m all ears.

  2. This is great stuff. Thank god we got statistics guys like you out there! Just to confirm, this can in other words mean that only 0.6% of games have had more of a free throw advantage for the home team. Thanks for giving me the notice about this though! Greatly appreciate!

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  4. Thanks for answering my question. That really is a large discrepancy.

    Since you arrived at this answer so quickly, you must have some kind of database of statistics in place. Being a database guy myself, I’m very interested to hear what kind of system/tools you are using to store the stats, run the reports, and prepare the graphs&charts.

  5. Paul: I do have a database: it’s nothing fancy, just a .CSV of every player’s box score line in every regular season game from 86-87 on. I also have season-level data since 1947.

    I use R statistical software to do all the math and make all the graphs. I’d recommend it to everyone; it’s free. It’s nothing fancy, but it works for me.

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