Monday, January 20, 2014

Geographic Analysis of Superbowl Winners: No Temperature, Distance or Time Zone Effects

In sports, even in championship games that are supposedly on neutral ground, some teams are thought to have home advantage if they play in or near their home state, for whatever reason; cultural similarity, less wear and tear from traveling, etc.. Do we see this in Superbowls?[1] (I didn't find any effects here so you can scroll up for a little more interesting one on ratings if you want.)

Not really. The winners, on average, have actually had to go a little farther from home than the losers (winners are on average 1487 miles from home, losers 1409, using Google maps driving distance to approximate.) And the home-state advantage, so far as it's happened - only four times so far, all with California teams playing in Cali - is a wash (2 wins, 2 losses). I also checked to see if the curve is U shaped, inverted or otherwise. For instance, if it's inverted U, maybe it's rough to take a 400 mile bus ride since further than that, you fly, and a full transcontinental flight is dehydrating and stiffening. But no dice. (If I cared, I would look at overall NFL records, not just the Superbowl, unless we're assuming the Superbowl is different.)

Above: distribution of Superbowl Games I through XLVII

Above: Superbowl wins and losses (#wins and losses proportional to radius of circle)

Seeing the maps above, you can tell that Superbowls and Superbowl teams are not distributed randomly. There's an obvious bias to the Northeast, as would be expected based on population density (and bigger markets). These maps show wins by CITY, not franchise (unless the franchises have remained stable and separate - so Jets and Giants are separate, but L.A. Raiders and Rams are not). But all things being equal, this should come out in the wash anyway.

So what about time zone changes? There's a known effect in sports called circadian advantage; it's assumed in medicine that we can adjust our circadian rates up or down 5%, so that we can adjust to one hour of time difference for each day. In fact in a peer-reviewed 1997 paper on Monday night football game advantage in the NFL, it was shown that West Coast teams do significantly better over East Coast teams than Vegas odds predict. (Note this is for night games, as would be expected.) It turns out that there is a slight but not significant difference overall: counting the Eastern time zone as 1, Central as 2, Mountain as 3 and Pacific as 4, Superbowl winners are from a little bit further east, with an average time zone of 1.8 vs the losers' average time zone of 1.9. There was no association between score margin and time zone either. I also checked to see whether there was any advantage to being closer to the time zone of the Superbowl location, or being from an earlier or later time zone, but there was not (the distribution was just about exactly coin-toss random).

While we're worrying about environmental factors, we might as well look at temperature - the home field's December average temperature, against the temperature on the field at the Superbowl. There is no clear curve for any relationship I checked (team's home December average temperature vs points scored, or difference from Superbowl city average temperature vs points scored.) There is a slight difference in terms of average "distance" (could be warmer or colder) between a team's home city, and the Superbowl city: winning teams are 20.9 degrees Fahrenheit off from the Superbowl temperature, and losers are 23.4 degrees off. In non-absolute value terms, the winners are on average 19.2 degrees colder at home vs the Superbowl, and the losers are 21.2 degrees colder at home.

What does this tell you about the Seahawks-Broncos matchup? Nothing! Who cares!

[1] Yeah, I said Superbowl. Not "big game". S-U-P-E-R-B-O-W-L, as in NFL. Listening to commercials you'd think saying Superbowl summons He Who Cannot Be Named or something.

[2] Smith RS, Guilleminault C, Efron B. Circadian rhythms and enhanced athletic performance in the National Football League. Sleep. 1997 May;20(5):362-5.

No comments: