A statistical look at last year's referees

Since a favorite hobby of sports fans is criticizing the officiating, I wanted to take a look at how the NBA's referees did last year. I pulled information on Games Refereed, Home Win %, Total Points Per Game, Total Fouls Per Game, Home and Road Foul %, and Home and Road Technicals Per Game. Through the miracles of spreadsheet software, I calculated the mean and standard deviation for each. I then set the boundaries for "normal" at 2 standard deviations, since 95% of all occurrences should be within 2 standard deviations if it's a standard normal distribution. All referees officiated at least 30 games, which gives a large enough sample size to be meaningful (Michael Smith officiated the fewest games, at 36). Numbers after the jump.

The average number of games officiated was 59.39, with a 7.8 game standard deviation. Nobody was more than 2 deviations over the mean. Under were Bill Spooner (41 games), Jack Nies (42 games), and the aforementioned Michael Smith.

Home Win % surprised me - it was a solid 60.66%, with a standard deviation of 6.73%, so "normal" referees would call home wins between 47.19% and 74.13%. The only "deviant" here was Curtis Blair. Home teams won only 44.7% of the 47 games he officiated.

Home Points Differential, not surprisingly, was positive. The mean was 3.18 points, with a standard deviation of 1.60 points, so "normal" ranges from -0.02 to 6.37. The three deviants here were all low, being Bill Spooner (-0.8), Curtis Blair (-1.7), and Michael Smith (-1.4)

Total points had a mean of 199.92, with a standard deviation of 2.67 points. The normal is 194.57 to 205.26, and every single referee fell within this range.

Fouls per game had a mean of 42.08, with a standard deviation of 1.41. Normal was 39.26 to 44.90 fouls per game. This stat had four deviants, again all low. David Guthrie (38.4), Gary Zielinski (39.2), Ken Mauer (39.0), and Steve Javie (38.8) were on the most lenient crews in basketball.

Road Foul % averaged 50.96%, with a standard deviation of 0.81%, meaning the range was 49.34% to 52.59%. There were three deviants, one low and two high. The low was Violet Palmer, whose crews called only 48.8% of fouls against the road team. High were Courtney Kirkland (52.6%) and Ron Garretson (52.8%).

Road Technical Fouls averaged 0.81, with deviation 0.14. Normal is 0.53 to 1.08. The only low was Ron Olesiak, at 0.5. High were Joe Forte (1.1), Ed Malloy (1.1), and Eli Roe (1.2).

Home Technical Fouls averaged 0.73, with deviation 0.15. Normal is 0.44 to 1.02. Derrick Collins was low at 0.40, Monty McCutchen was high at 1.1.

Thoughts: This was designed to catch the referees who fall outside the 95% bounds of normality. This isn't a measure of who is a good or bad referee (since the games referees are assigned could skew their numbers), but it can give an idea of who to watch for when referees are announced for a game. A crew of Forte, Malloy, and Roe could be expected to call more technicals on the road team than normal. A Javie/Mauer/Guthrie crew will be like rec yard basketball, with few fouls.