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September 01, 2009
Home Field Advantage
Here's a fun one. What if we looked at all the scores of NFL games since 2001 and compared the score of the Home Team versus the Away team. Does being the home team give you an advantage? Short answer: Yes! On average the home team scores about 2.5 points more than the away team.
In terms of stats, we can use a t.test to compare the home scores versus the away scores (normally, we could use a z-test but I'm guessing the scores aren't normally distributed).
A basic analysis using R (just google the letter R) reveals:
Welch Two Sample t-test t = 9.2216, df = 5357.6, p-value < 2.2e-16 95 percent confidence interval: 1.978520 3.046853 sample estimates: mean of x mean of y 21.81978 19.30709
Our 95% confidence interval is between 1.97 and 3.04 points per game. Over the course of a whole season, I can see having more active players on home games can lend a small advantage.
This leads to a different question. When drafting your team, it seems like it would be advantageous to obtain players with alternating home games. For example, if you had two quarterbacks that played home games on alternating weeks. More on this coming shortly.
Update: Thinking quickly about it, I realized that Super Bowl games don't have terribly much of a home field advantage, given that they are in a neutral third party city usually. With those games removed, our numbers are adjusted slighly but trivially: {1.98, 3.06}
Posted by haydenth at September 1, 2009 12:02 PM