Splitting the Uprights – Easier Indoors?

By Jonathan Adler

In Super Bowl XXXVI, New England kicker Adam Vinatieri’s 48-yard field goal attempt sailed through the uprights, clinching a world championship for the Patriots. Nearly eleven years before Vinatieri’s kick, Scott Norwood’s 47-yard field goal attempt in Super Bowl XXV famously missed “wide right” and earned the Buffalo Bills their first of four straight Super Bowl losses. One major difference between these two events in football history: Vinatieri kicked inside the Louisiana Superdome, while Norwood lined up outside in Tampa.

Conventional wisdom argues that field goal kickers will experience greater success indoors compared to outdoors – that domes are better for attempting field goals. The purpose of this brief analysis is to examine whether there is, in fact, an association between being indoors and kicking success.

My analysis uses data from STATS Inc. for each NFL game in the 1998-2008 regular seasons. Rather than simply compare all indoor field goal attempts to all outdoor field goal attempts, the nearly 10,000 FG attempts between 1998 and 2008 were separated into five categories: FG attempts between 1-19 yards, 20-29 yards, 30-39 yards, 40-49 yards, and 50+ yards. Within these groupings, a chi-squared test was conducted at the 0.05 significance level to determine whether there is an association between field goal success and kicking indoors.

For FGs attempted from a distance of less than 20 yards, kicking indoors was not significantly associated with FG success (p=1.000). For FGs attempted from a distance between 20-29 yards, kicking indoors was significantly associated with FG success (p=0.006). The association was also significant from distances of 30-39 yards (p=0.003), 40-49 yards (p=0.001), and 50+ yards (p=0.01).

Not surprisingly, there is a strong association between kicking indoors and greater FG success. From distances of greater than 20 yards, being indoors is strongly associated with higher FG success. And the significance of this association appears to increase along with the length of the FG attempt. However, the association weakens for FG attempts from more than 50 yards out. It might be that from distances greater than 50 yards, kicking from inside/outside is less important compared to a kicker’s leg strength and the line’s blocking abilities. The association is not significant for FGs attempted from less than 20 yards out – it seems that whether kicking inside or out is negligible at such an easy distance (only 4 field goals were missed from less than 20 yards in the past decade, and a few of those may have been blocked).

So it seems that Buffalo’s Scott Norwood, as he massages an empty patch of skin on his ring finger, can rightly consider the role of kicking outdoors and his botched 47-yard attempt, while Adam Vinatieri can be grateful that Super Bowl XXXVI was played indoors.

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7 Responses to Splitting the Uprights – Easier Indoors?

  1. dadler3 says:

    One possible reason the distinction breaks down for field goals of 50+ yards is that only the good kickers receive the chance to attempt long kicks outdoors while the less skilled kickers may get a chance to try from 50+ in a dome. Essentially, we have a selection bias as those who kick from 50+ outside are a different group (more skilled on average) than those who kick from 50+ inside.

    So if we compared the “skilled” kickers outdoors from 50+ to the same group indoors from 50+, my guess would be that long kicks would prove to be easier indoors.

  2. BlueStarDude says:

    But how much would the difference be diminished if you compared kicking indoors to kicking outdoors in “warm weather” stadiums?

    Re: the Norwood example: It would seem that kicking outdoors in Tampa on a Super Bowl-prepared field is about as close as you can get to dome conditions.

    P.S. Nice blog.

  3. jmaron says:

    re: 50+ FGs

    Wind. Teams don’t try 50+ yarders outside unless they have favourable wind conditions. A 50 yarder with a 20 mph tail wind may well even up other factors that make kicking indoor easier.

  4. Matt says:

    Thank goodness we now have detailed statistical analyses suggesting that kicking in a dome is easier than kicking outside. That one seems obvious, but it’s always good to dress up simple answers with numbers.

    • Kevin says:

      Matt – great idea, continue to follow conventional wisdom without looking to find out the facts. Brilliant. I’m sure your input is very useful – please, continue

  5. Dadso says:

    Wonderful analysis, but one fact sticks in my craw. “Only 4 FGs missed from less than 20 yds in the past decade”? Including blocks? What about blown snaps?
    Why didn’t you apply the ambient temperature and hence atmospheric density to the equation? Bravo!

  6. Pingback: Atlanta’s Math Might Check Out | Augusta Blog

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