Saturday, January 21, 2006

Homefield Advantage in the Big 10

Sometime ago, I posted an entry on NCAA teams that played in domes and their collective struggles away from home. I had been meaning to do some more research on the subject, but got sidetracked by other obligations. Since only one dome team (Minnesota) plays in a major conference that has not been radically altered by teams shifting to and from other conferences, I decided to look at the cummulative Big 10 conference record of every team since 2000. I chose only conference records because each team has different non-conference schedules (both in quality and quantity). The sample size of 6 seasons gives us 48 total games (24 home and 24 road) for each team and helps eliminate some of the volatility of a conference season that does not include every opponent. First up, the home record of each Big 10 team since 2000 from best to worst.
  1. Iowa 20-4
  2. Michigan 20-4
  3. Ohio St. 19-5
  4. Purdue 17-7
  5. Minnesota 14-10
  6. Northwestern 14-10
  7. Penn St. 14-10
  8. Michigan St. 12-12
  9. Wisconsin 12-12
  10. Illinois 9-15
  11. Indiana 8-16

Now the road warriors.

  1. Michigan 17-7
  2. Ohio St. 16-8
  3. Iowa 12-12
  4. Wisconsin 12-12
  5. Purdue 10-14
  6. Northwestern 9-15
  7. Penn State 9-15
  8. Minnesota 7-17
  9. Michigan State 6-18
  10. Illinois 5-19
  11. Indiana 2-22

Here are the leaders in delta points at home. Delta points are net points. Michigans +348 means they have outscored their home opponents by 348 points (roughly 14.5 per game).

  1. Michigan 348
  2. Ohio St. 324
  3. Iowa 311
  4. Penn St. 238
  5. Purdue 218
  6. Minnesota 165
  7. Michigan St. 76
  8. Wisconsin 67
  9. Northwestern -66
  10. Illinois -181
  11. Indiana -200

Now the leaders in road delta points.

  1. Michigan 145
  2. Ohio St. 115
  3. Iowa 29
  4. Wisconsin -15
  5. Purdue -36
  6. Penn St. -74
  7. Minnesota -189
  8. Michigan St. -193
  9. Northwestern -218
  10. Illinois -379
  11. Indiana -487

Next up is a ranking of 'relative homefield advantage' by difference in home/road winning percentage. Iowa has the largest discrepancy in home and road play in this category, winning at an .833 clip at home (20-4) versus .500 on the road (12-12) for a difference of .333.

  1. Iowa .333
  2. Minnesota .292
  3. Purdue .292
  4. Indiana .25
  5. Michigan St. .25
  6. Northwestern .208
  7. Penn St. .208
  8. Illinois .167
  9. Michigan .125
  10. Ohio St. .125
  11. Wisconsin 0

Some observations. While Iowa has the greatest discrepancy in home and road winning percentage, Minnesota is still a close second, tied with Purdue. The 2 best teams in the conference in the decade of the 2000's Michigan and Ohio State, are nearly as capable of winning on the road as they are of winning at home. Of course, this does not mean they have only a small homefield advantage. On the contrary, it is only relatively smaller because they win so many road contests. I wonder if this fact is true in other conferences, do the elite teams have the smallest relative homefield advantage because they win so often on the road as well? Finally, in a surprising twist, Wisconsin has not enjoyed much of an advantage in Camp Randall Stadium as they have won the same amount of games away from home as well. Wisconsin does not fall into this 'elite' category as they are only 12-12 at home and on the road.

Finally, here is a ranking of 'relative homefield advantage' by difference in delta points at home and on the road. Minnesota has the largest discrepancy in home and road play in this category. They have 165 delta points at home and -189 on the road for a difference of 354 delta points.

  1. Minnesota 354
  2. Penn St. 312
  3. Indiana 287
  4. Iowa 282
  5. Michigan St. 269
  6. Purdue 254
  7. Ohio St. 209
  8. Michigan 203
  9. Illinois 198
  10. Northwestern 152
  11. Wisconsin 82

From this second set of data, Minnesota has arguably the top discrepancy in home and road play. While Iowa is a respectable 12-12 on the road, they are a remarkable 20-4 at home. Minnesota on the other hand is above average at home (14-10), but quite below average on the road (7-17). Again, Wisconsin does not appear to have enjoyed a significant advantage playing at home in the past 6 years. I plan on looking at other conferences in the near future as well. As usual, any comments and questions are welcome.


Anonymous said...

Your final ranking is really nothing but a record of teams that are inconsistent and rely completely on home advantage for a win. While that is a part of home-field advantage, it completely discounts Michigan and Ohio State simply because they consistently win home and away.
Really, you need to take a statistics class for these things.
All this tells me is that Iowa plays poorly on the road.

matt said...

I believe you did not look at the data or read my analysis. About Ohio St. and Michigan I wrote:

'Of course, this does not mean they have only a small homefield advantage. On the contrary, it is only relatively smaller because they win so many road contests.'

Additionally Iowa, while a Big 10 best 20-4 at home is also 12-12 on the road. Only 2 teams in the Big 10 have a better road record during this time span, so I would hardly call this playing poorly. Perhaps you need to take a reading comprehension class for these things.

STR said...

You should discuss one day the reasons why home field gives teams an advantage. Influences calls on Referees, unusual environment on the road team, and etc. But anyways ,great blog, cant wait to see an ACC and SEC one done.

Trader Kevin said...

You might be interested in this article from the Journal of Quantitative Analysis in Sports. (Free registration required.)

If you have a problem accessing it, send a message to the "List owner" email address of my Web site and I'll email it to you as a PDF.

Anonymous said...

Would it be fair to say, from your analysis, that a Michigan team that is 1 point better then Ohio State on a neutral site, should expect to lose at Ohio State by more then 3 points?