NFL Referee Statistics: Correlations within the same season

Let's look for correlations within the same NFL season for NFL referee statistics. Let's line up the referees for their statistics from weeks 1-5 and then line them up for their statistics from weeks 6-10 and see if there are correlations between how they are distributed for weeks 1-5 and weeks 6-10. If there is a strong correlation, then it seems the order they were for their work from weeks 1-5 was a perfect predictor for how they would be ordered for their work in weeks 6-10. This analysis is not looking between statistics of different seasons (we're not checking the 2007 NFL referee statistics for this).

Strong correlations between weeks 1-5 and weeks 6-10 for:
Percent penalties against visiting teams (0.338)
Percent penalty yards against visiting teams (0.343)
Total points scored (0.219)
Total points scored by teh home team (0.253)
Penalties against the home team (0.112)

No correlation for a few categories:
Home team winning rate (0.036)
Total number of accepted penalties (0.009)
Penalties against the visiting team (-0.026)

A negative correlation for a few categories:
Points scored by the visiting team (-0.184)
Total penalty yards (-0.137)
Average yards per penalty (-0.130)

Intriguing or just a bunch of random statistics?

NFL Referee Statistics After Week 10 (through games of 11/10/08)

Just a quick update this week -- this includes all the games of week 10, through the game on Monday, November 10, 2008.

No narrative explanation (anything you would like to focus on next time?). Just some statistics this time:

Referee, Penalties accepted per game, Penalty yards accepted per game, Yards per penalty accepted, % of accepted penalties against the visiting team, % of accepted penalty yards against the visiting team, total points scored.

Anderson, Walt 13.0 99 7.6 54% 54% 36.5
Boger, Jerome 15.2 113 7.4 43% 41% 44.8
Carey, Mike 10.3 88 8.5 43% 43% 41.1
Carollo, William 11.4 89 7.8 52% 55% 41.4
Cheffers, Carl 10.1 85 8.4 42% 35% 45.8
Coleman, Walt 8.8 69 7.8 63% 65% 44.1
Corrente, Tony 13.7 126 9.2 50% 53% 42.7
Green, Scott 10.8 75 7.0 53% 53% 47.5
Hochuli, Ed 12.7 102 8.1 51% 45% 47.2
Leavy, Bill 10.5 81 7.7 55% 53% 48.1
McAulay, Terry 11.6 97 8.4 47% 43% 48.2
Morelli, Peter 10.8 77 7.1 53% 56% 49.8
Parry, John 12.3 93 7.6 51% 48% 42.6
Riveron, Alberto 11.6 99 8.6 46% 46% 44.1
Steratore, Gene 10.1 79 7.8 58% 58% 40.2
Triplette, Jeff 15.1 117 7.7 46% 41% 42.5
Winter, Ron 14.0 114 8.1 48% 50% 49.1

NFL Referee Statistics: Correlations from Season to Season

Which statistics for NFL referees seem to hold up from season to season? Let's test this by looking at the correlation across the spread of referees from one season to the next. For example, if the ranking of which referees have the highest accepted penalties per game is the same from one season to the next, we would see a strong correlation from year to year.

This is based on a comparison of the 2007 season to the first 9 weeks of the 2008 season and also a comparison of the 2006 season to the 2007 season.

Total accepted penalties per game has a strong correlation from year to year: 0.503 from 2007 to 2008 so-far and 0.392 from 2006 to 2007. Same for total accepted penalty yards per game with 0.516 for 2007 to 2008 so-far and 0.394 for 2006 to 2007.

So it seems that some referee crews year in and year out consistently call more penalties than other referee crews. Maybe some are sticklers for the rules and others let things slide.

There is also a correlation across the years for the number of accepted penalties called against the visiting team (0.275 this year and 0.123 last year), accepted penalty yards against visiting teams (0.236 this year and 0.332 last year), accepted penalties against home teams (0.298 this year and 0.489 last year), and to some degree accepted penalty yards against home teams (0.088 this year and 0.417 last year).

There is no correlation from year to year for the home team's win rate so far (this year 0.009 and last year -0.172). One point, though, is that there is such a small sample size. After the first eight weeks, Peter Morelli went from the referee where the home team did the worst in 2007 (33% win rate) to the opposite -- the referee after the first nine weeks where the home team has done the best (93% win rate!). If we took out Peter Morelli, the correlation would jump from 0.009 to 0.335 -- so let's see how it shapes up the rest of the year. Considering the correlation between 2006 and 2007 was negative, I am not expecting it to climb by much. But the adventures of Pete Morelli's home win rate continue...

NFL Referee Statistics after Week 9 (after games of 11/3/2008)

Just a quick update this week -- this includes all the games of week 9, through the game on Monday, November 3, 2008.

No narrative explanation (anything you would like to focus on next time?). Just some statistics this time:

Referee, Penalties accepted per game, Penalty yards accepted per game, Yards per penalty accepted, % of accepted penalties against the visiting team, % of accepted penalty yards against the visiting team, total points scored.

Anderson, Walt 13.0 99 7.59 53.8% 53.6% 36.5
Boger, Jerome 15.0 111 7.38 43.3% 40.3% 43.6
Carey, Mike 9.7 82 8.47 46.6% 45.2% 44.2
Carollo, William 11.8 94 7.99 53.2% 55.5% 40.4
Cheffers, Carl 10.0 86 8.63 41.4% 33.8% 44.9
Coleman, Walt 9.3 73 7.84 63.5% 65.7% 45.9
Corrente, Tony 12.9 121 9.41 49.5% 52.5% 41.4
Green, Scott 10.8 75 6.99 53.5% 53.2% 47.5
Hochuli, Ed 12.9 106 8.21 48.5% 42.2% 48.8
Leavy, Bill 11.1 85 7.64 55.1% 52.9% 45.9
McAulay, Terry 11.9 99 8.37 47.4% 43.8% 45.9
Morelli, Peter 11.0 80 7.26 53.2% 57.1% 51.1
Parry, John 12.7 97 7.62 49.4% 46.2% 42.4
Riveron, Alberto 10.9 95 8.74 43.7% 44.2% 42.8
Steratore, Gene 10.3 80 7.77 56.1% 57.8% 38.5
Triplette, Jeff 15.1 117 7.72 46.3% 40.8% 42.5
Winter, Ron 14.8 121 8.23 48.3% 51.6% 50.4

NFL Referee Statistics: Net Total Points Per Game

After 8 weeks (on 11/1/2008, just before Week 9 begins), let's take a look at which referees have the highest-scoring games compared to what you would expect from the particular teams on that referee's schedule. Just as team statistics include adjustments for the strength of the opponent, let's adjust the referee statistics by the strength of the two teams involved.

This way, if a referee has a schedule packed with high-scoring teams, we can filter that out in seeing whether his games are higher scoring than usual.

Here we go!

Net Total Points (with team adjustments) as of 11/1/2008:
Ron Winter (+5.4), 51.4 raw total points
Peter Morelli (+4.5), 51.3
Ed Hochuli (+4.3), 47.6
Carl Cheffers (+3.7), 47.5
Terry McAulay, (+3), 46.7
Bill Leavy (+2.9), 47.7

referees where you might consider taking the under if you bet the over/under for total points:

Walt Anderson (-5.5), 38.3
Gene Steratore (-5.2), 38.5
Jeff Triplette (-3.2), 41.9
Tony Corrente (-3.0), 41.1
John Parry (-1.7), 42.4

When we account for team adjustments, the top two remain the same but Bill Leavy falls from third in raw total points to sixth in net total points. This is because three other referees that sneak ahead of him in net total points covered games with teams that overall had lower-scoring games than the average.

Looking at the bottom, the bottom two remain the same but Jeff Triplette leaps from 5th-lowest in raw total points to third-lowest in net total points. This is a combination of how his teams had slightly more than usual total expected points (45.1) and Tony Corrente (44.2) and William Carollo (43) had slightly lower-scoring teams in their games.

No major or drastic differences, though, for the rankings between raw total points and net as compared to the teams involved.

NFL Referee Statistics After Week 8 (Updated 11/1/2008)

Let's go through some interesting categories for 2008 NFL referee statistics:

Total accepted penalties

Jeff Triplette (15.3) lost most of his lead over Ron Winter (15.1) and Jerome Boger (14.7).

Walt Coleman (9.4) still at the bottom, in front of Scott Green (10.1) and Carl Cheffers (10.2).

Total penalty yards

Ron Winter (127) keeps his lead over Tony Corrente (121) with Jeff Triplette down in third at (118).
Scott Green (75) and Walt Coleman (75) in a virtual tie at the bottom.

Yards per penalty

Tony Corrente (932) again extends his lead over Alberto Riveron (8.7) and Terry McAulay (8.6)

Peter Morelli (7.1) a bit more ahead of Jerome Boger and Scott Green (7.4).

Points per game (no team adjustments)

These are raw numbers, not adjusted for the teams who played in the games.

Ron Winter (51.4) is almost caught by Peter Morelli (51.3) followed by Bill Leavy, Ed Hochuli, and Carl Cheffers (each in the 47.5-47.7 range).

Walt Anderson (38.3) takes over the bottom with Gene Steratore (38.5) close behind. Tony Corrente plummeted to third from 36.5 last week to 41.1 this week. That's what a jolly old week in London for a high-scoring 37-32 game between New Orleans and San Diego will do to your statistics.

Week 9 Cheatsheet

Referee, penalties, penalty yards, yards per penalty, and total points:
Anderson, Walt 13.3 99.1 7.46 38.3
Boger, Jerome 14.7 109.4 7.44 42.9
Carey, Mike 10.6 91.2 8.60 46.4
Carollo, William 13.0 104.4 8.03 41.4
Cheffers, Carl 10.2 80.8 7.95 47.5
Coleman, Walt 9.4 75.0 7.95 45.4
Corrente, Tony 13.0 120.9 9.30 41.1
Green, Scott 10.1 74.6 7.35 45.1
Hochuli, Ed 12.7 105.6 8.30 47.6
Leavy, Bill 12.0 90.0 7.50 47.7
McAulay, Terry 11.1 95.7 8.59 46.7
Morelli, Peter 11.7 83.0 7.11 51.3
Parry, John 12.7 96.9 7.62 42.4
Riveron, Alberto 10.9 95.0 8.74 42.8
Steratore, Gene 10.3 79.6 7.77 38.5
Triplette, Jeff 15.3 117.7 7.70 41.9
Winter, Ron 15.1 127.4 8.42 51.4