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Home cookin?

Posted by Doug on May 19, 2006

You know what I hate?

The quarterback sneak.

I acknowledge that it's generally a pretty effective play if you need to pick up two inches. But it's really ugly. And besides that, it puts the refs in a tough spot. On most quarterback sneaks, it's impossible to get a decent spot because no one --- not the refs, the fans, or even the TV cameras --- can see through the pile of bodies well enough to pinpoint the exact spot of the ball (which you can't see) at the time that the knee (which you can't see) touches the ground (which you can't see) or figure out when the forward momentum of the ball carrier was stopped. It just can't be done. And the result is that the ref has to arbitrarily decide whether to award a first down or not.

That makes me wonder whether the arbitrary spots that the home team gets might be different from the arbitrary spots that the road team gets. I decided to take a very incomplete preliminary look at some data to see if anything interesting would turn up. And, though I started this post talking about quarterback sneaks, I'm going to open up the data to the broader topic of short-yardage situations.

So here is what I did. I looked at all 3rd-and-1 and 4th-and-1 situations during the past three seasons in which a rush was attempted and where the rush gained either zero or one yard. Inasmuch as we can tell from the play-by-play data, those would be the plays where a spot could make the difference. Here is the data:


attempts successes success rate
===============================================
home team 357 174 48.7%
road team 390 159 40.8%
===============================================
TOTAL 747 333 44.6%
===============================================

Given the sample sizes involved, it's very unlikely that such a split would happen by chance if the true success rates were equal. So we have pretty good evidence that the success rates are not the same. It's pretty likely that something is going on here.

I need to state clearly that this does not necessarily say anything about the refs and whether their spotting guesses are influenced by the home crowd. The refs are just one of many possibilities for the something that is going on. Teams in all sports do all sorts of things better at home than on the road, so this could be just another non-officiating-related manifestation of that slippery character named home field advantage.

Or maybe it's not. This data isn't merely saying that the home team converts more often on 3rd-and-1. It's saying that they convert more often on 3rd-and-1 when the play is close. I don't think it's possible to statistically separate the officiating-related home field advantage (if any) from the non-officiated-related home field advantage, so we'll never know. But this looks a bit suspicious to my paranoid eye.

I think sports rooting is a good outlet for me to release all my irrationality. Most people who know me consider me pretty logical and level-headed, and generally I am. As I sit here typing this, I truly believe that "this does not necessarily say anything about the refs and whether their spotting guesses are influenced by the home crowd. The refs are just one of many possibilities for the something that is going on." But the first time a team I'm rooting for gets a bad spot on the road, this data will become iron-clad evidence of widespread conspiracy.

That's healthy, right?

This entry was posted on Friday, May 19th, 2006 at 4:40 am and is filed under Home Field Advantage. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.