Who covers the spread?

by Greg Lamp

Interstingly enough, it seems not all teams are staked equally. While most teams cover between 45%-55% (or about half) of their games, there are a few teams you might want to stay away from (or not bet against).

Step 1: Data collection... There are plenty of sites that offer historical spreads for college football games. I wrote a quick screen scraper using Python that collected the team, spread, score, and date for each game and each team since 1985. It was pretty basic--just BeautifulSoup writing to a csv.

Step 2: Loading it into R... Next I wanted to take a look at the relationship between the Vegas spreads vs the acutal results of the games. As you might expect things looked pretty normal.

I wound up limiting to games played since 2000 to make the sample a little more consistent. Controlling for some other variables like week of the season and year didn't seem to make much difference. There were a few long tail events out to the right, but nothing mind blowing.

So far nothing spectacular. But when you drill down into each team, things start to get a little bit more interesting. As mentioned earlier, most teams wind up somewhere right around the 50% mark. But a few teams stick out... Boise St., everyone's favorite small conference bully, covers a whopping 61% of spreads. Not very surprising since they have to show off against the likes of Idaho and Wyoming in order to make an impression on the Coaches and AP polls. UCONN (61%) and Washington (37%) also stand out, but to be honest I'm not sure what to make of them. Oddly enough, arch rivals Ohio State and Michigan wind up at opposite ends of the spectrum with Michigan near the bottom and Ohio State at #3.