Confirmation Bias

Confirmation Bias: or, why Duke is No. 8

The new AP and USA Today polls were released today and Duke was No. 8 in both polls. This caused Jay Bilas to tweet out a "stat not often considered," by which I assume he means it is a fact that is mentioned every single time Duke takes the court.

While this is an amazing accomplishment of consistency in the program, the bigger question is why is this team ranked in the top 10?

Voters spit out their criteria ad nauseum, which is always something along the lines of rankings by resume. You have to rank the teams by what they've done on the court.

And what has Duke done on the court? They're 7-2. They've played two teams rated in Pomeroy's top 20 and have lost to both on a neutral court. They've beaten No. 23 Michigan (using Pomeroy's ratings for the rest of this discussion, as it is the best, unbiased, ranking their is, and if you don't believe me just ask all the gamblers in Vegas) and No. 43 Alabama. Every other team they've played has been rated > 150.

So they're 2-2 against top 50 teams.

Big whoop.

Wichita State (AP No. 11) is 10-0 and have beaten three top 50 teams.

Baylor (AP No. 12) is 8-1 with a loss to No. 7 Syracuse, a win over Kentucky (11), Colorado (31), and Dayton (45).

Memphis (AP No. 15) has one loss to No. 3 Oklahoma State, and they also have wins over Oklahoma State and LSU (44).

Iowa State (AP No. 17) also beat Michigan – who is Duke's signature win – but they've also beaten Iowa (13) and BYU (49).

UMass (AP No. 22) is 9-0 with four wins over top 50 teams.

I could go on.

So why is Duke No. 8?

It's called confirmation bias. Confirmation bias is the tendency of people to favor information that confirms their beliefs. Duke was the preseason No. 4 team in the nation. So, as they've struggled out of the gate, voters have never re-evaluated that No. 4. Voters just assume that they were right, and that Duke being No. 4 was a fact rather than a random assemblage of opinions. So when Duke loses they drop them a few spots. And when Iowa State – who was unranked in the preseason – puts together a much better resume than Duke, they end up 9 spots behind them. Confirmation bias strengthens beliefs in the face of contrary evidence.

If voters claim that they vote based on resumes, then now would be a good time to implement those beliefs. But don't count on it.

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