The Patriots and Confirmation Bias

by Russ Roberts on May 13, 2015

in Data, Sports

I really wanted the Wells Report to exonerate the Patriots. It did not. So being a huge Patriots fan, I read the Report carefully hoping to find a flaw. At first, I thought the engineering consulting firm, Exponent, had left a huge puzzle unexplored–while it’s true that the Pats balls apparently deflated a lot more than the Colts balls after being used in the first half, they seemed to deflate a lot less than the physics would predict. This would imply some kind of measurement error.

But I was wrong. The study DID take that into account. They explained by pointing out that the Colts balls had spent more time in the toasty halftime locker room so they had a chance to warm up more and pressure measurements were indeed consistent.

So I thought some more and looked for a different flaw.

This is what confirmation bias is good for. It’s what ideology is good for. It helps you identify hypotheses you might not have thought of. To see it in action, the Patriots haters see the texts uncovered in the Wells Report as definitive. They can’t imagine an innocent explanation. But as a Patriots fan, I can. What matters then is how far-fetched or illogical my explanation is. For after all, I am a fan. I’m biased. So bias can have a value, but of course it’s dangerous. It’s prone to make you think you’re alternative explanation, no matter how far-fetched, is perfectly logical.

I found another flaw. At first I thought it was devastating. I thought so for hours. I couldn’t wait to publish it. But being sensitive to my bias, I did wait and chewed on it some more. At some point, I realized I had over-estimated its importance. It matters, just not as much as I had thought at first. It was a great exercise in restraint which is not my strong suit.

The bottom line is that it remains the case that the Patriots may have cheated and probably deserve punishment of some kind. But the actual data on the inflation levels of the Patriots balls over the course of the AFC Championship game isn’t as strong as the Wells Report suggest. If you’re interested in the details, here’s my take along with other observations I haven’t seen elsewhere. Patriots fans will find it somewhat comforting perhaps. Patriot haters will still be able to dismiss it, of course. Ah, bias.


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