A: I've heard that before as well, but I've never tested it to see if it's true. It would at first glance seem that there should be some truth to it - the AFC was strong in the 1970's and early 1980's, when the economy was weak, whereas the NFC was strong in the rest of the 1980's when the U.S. economy was strong. Let's take a look at the data to see what we can find.
First we need to get a list of the results from every Superbowl. That's easy enough to do - I used the ones posted by the Washington Post. Then we need data on the growth rate of GDP, which can be found at the Bureau of Economic Analysis.
To test the theory, I considered the first 39 Superbowls (including the ones before the AFL-NFL merger) and I created two variables. The first was a dummy variable which indicates which conference won the Superbowl. Our dummy variable equals '1' if the NFC team won and '0' if the AFC team one. I also wanted to see if the size of the victory was important - was a huge victory by an NFC team mean higher economic growth than a close NFC win? To do so I created a variable which is the difference between the NFC team's score and the AFC's team score. This value is positive if the NFC team, and negative if the AFC team was victorious.
Is there any correlation between an NFC victory and economic growth? Here's what I found:
Correlation between NFC win and Economic Growth: 0.074963
Correlation between Margin of Victory and Economic Growth: 0.123182.
So there is a statistical correlation between Superbowl results and economic growth. It's a very small relationship (which is to be expected, since the two variables should have nothing to do with each other in reality), but interestingly enough the margin of victory seems to matter - the more the NFC wins by the more the economy grows that year.
To get a better idea of the observed relationship between economic growth and the NFC margin of victory, I ran the following regression:
GDP growth = a + b * NFC point differential
My output was as follows:
GDP growth = 3.0457 + 0.01322 * NFC point differential
Thus before the Superbowl is played, we should expect there to be 3.05% growth of GDP during the year. We need to revise our prediction after the superbowl by 0.01322 per point of NFC point differential. Not surprisingly, this figure is not statistically significant, which we should expect, since the economy and the results of the Superbowl should have nothing to do with each other. But for the sake of argument, let's suppose the relationship is a valid one.
In Superbowl XL, played on February 5, 2006, the AFC's Steelers beat the NFC's Seahawks by the score of 21-10. This is considered an NFC point differential of -11 in our model.
Before the game was played, we should expect U.S. economic growth to be 3.0457%. After the game, this must be revised downward to 2.9003%. That may not look like a significant jump, but it would mean the loss of billions of dollars to the economy (relative to the higher growth rate). Fortunately the magazine The Economist is predicting the growth rate of GDP to be 3.3% for the next year. I'd wager that their estimate will end up being more reliable.
If you have a question about economics or economic growth, you can contact me by using the feedback form.