Sunday, November 01, 2009

Over/Under and Home-Team Referee Statistics from 2008 to 2009

Let's take a closer look at the over/under records for each referee who worked in the 2008 season and is now working in the 2009 NFL season.

We've charted out the over/under record for each referee in 2008 and 2009. Let's see if there is a correlation between how each one ranked in 2008 and how each one ranked in 2009 after the first 7 games of the season. There would be a strong correlation, for example, if the rankings in 2008 was the same as the ranking in 2009 (whoever had the best record for the over in 2008 also had the best record for the over in 2009).

However, the over/under correlation between 2008 and 2009 (after 7 games) is -0.213. That is a negative correlation, suggesting that if a referee had a great record for the over in 2008, the referee had a bad record for the over in 2009. That suggests perhaps the over/under is not so referee specific.

Next, we ran the same analysis in comparing the 2008 record for each referee and the 2009 record after 7 games if you always went with the home team when taking a position against the point spread (regardless of whether the home team was favored or the underdog).

The correlation for home team (against the spread) is even worse: -0.425. Maybe using this limited data, it is not suggesting that a particular referee is better for home teams across seasons against the spread.

To give you an idea how bad that correlation figure is, the figures between 2008 and 2009 so far are much higher for: total accepted penalties (0.574) and total accepted penalty yards (0.396).

Here are some examples on the over/under issue:
at the top:
Carl Cheffers: Over-2008 (73%) and Over-2009 so far (50%)
Bill Leavy: Over-2008 (67%) and Over-2009 so far (only 17%)

at the bottom:
Gene Steratore: Over-2008 (40%) and Over-2009 so far (a huge 100%)
Scott Green: Over-2008 (27%) and Over-2009 so far (57%)

Here are some examples on the home team against the spread:
at the top:
Alberto Riveron: Home Team ATS 2008 (63%) and Home Team ATS 2009 so far (50%)
Jerome Boger: 2008 (60%) and 2009 so far (only 14%)

at the bottom:
Scott Green: 2008 (33%) and 2009 so far (a huge 71%)
Gene Steratore: 2008 (33%) and 2009 so far (67%)
Ed Hochuli: 2008 (31%) and 2009 so far (33%)

Let's check in on this later in the season. If we see interesting correlation figures for other ways to analyze referees, we can post on it again on the blog.

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