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The dumb-blonde stereotype is a myth. And so is this scientific conclusion dispelling it.

There are so many reasons to be skeptical of a new viral study linking intelligence to hair color.

Screen Capture /Photo Illustration

Economist Jay Zagorsky recently set out to debunk a dumb myth: that blond women are not as smart as the rest of the population.

He found a large database of randomly sampled adults that contained information on both hair color and intelligence. He crunched some numbers — and got an astounding answer.

"Among white women, those reporting having blond hair are actually slightly smarter than those with other hair colors," he writes in a new paper published in the Economic Bulletin, an open access peer-reviewed journal.

That type of counterintuitive conclusion — not only are blond women not dumb, they're actually smarter! — is media catnip. Stories trumpeting the results declared:

"Science Definitively Proves Blondes Aren't Dumb"

"Turns Out Blonde Ladies Are the Smartest"

"Study: Despite the jokes, blondes aren't dumb"

(There were many, many other articles written about this study.)

It's news candy, for sure. But here's why you should spit it right out: That conclusion is really, really dubious.

At first glance, there are reasons to want to take the results seriously

This study has several attributes that lend it credibility. Here are a few:

  • The study was published in a peer-reviewed academic journal.
  • The author is a research scientist at the Ohio State University.
  • The data was obtained from a large, randomly sampled survey of more than 10,000 young Americans.
  • The data set contained information on the participants' self-reported hair color and their results of a military-issued intelligence test. This makes a one-to-one comparison possible.
  • The results were statistically significant.

But there are a great many more reasons to be skeptical

I called up Regina Nuzzo, a statistics professor at Gallaudet University, to go over the merits of the study. "I'm calling statistical shenanigans on this," she told me, flat out. She explained how to debunk the claim that blondes are the smartest hair type one step at a time.

First off: Zagorsky did not find any statistical difference between blondes and brunettes. It's just not reported in his data. Just that fact alone debunks the assertion that blondes are the smartest hair type!

Now on to redheads. There, he found a significant difference, but only by inflating the definition. Usually, the standard for significance is a value of .05. But when he compares blond women and redheads, he reports a value between .05 and .10. Most scientists would say this is not significant.

In his comparison of black-haired women to blondes, he does find a significant .05 difference. But, this too can be debunked. He used what's known as a one-sided test, which statisticians frown upon. In this case, a one-sided test only allows him to test the idea that blonds are smarter. A two-sided test would be better: it would also account for the possibility black haired women are smarter. If you were to conduct a two-sided test with this data, Nuzzo says, you'll find the significant difference goes away. And it becomes very plausible that black-haired women may actually be smarter.1

Another reason to doubt the sample's ability to generalize: How is it possible that there are so many more black-haired men in the study than black-haired women? In the paper, Zagorsky suggests "3.5 percent of women did not follow directions and reported their current hair color instead of their natural color."

Oh, and one more: The data for this study was collected in the 1970s and 1980s. Which doesn't mean the data is bad, but possibly less relevant today.

Which brings us to a final point: These IQ averages are already indistinguishable from one another

Broadly, differences in IQ are linked to academic achievement — but not at such small scales. Differences between people who have IQs of 80 and 120 may be meaningful (an IQ of 100 is considered average). But not differences between 100.1 and 103.2. Those scores are practically identical, even if a statistical analysis claims to find a difference.

I reached out to Zagorsky over email to clear some of this up. He said the point of the study wasn't to show that blondes are smarter, but to show that the dumb-blonde stereotype is a myth. "If believing in something silly like blondes are dumb is not true, imagine how many other prejudices are also wrong?" he writes.

And he clarifies his study is not the final word on the intelligence of blondes. "This does not prove (nothing can be proven in social science research) that blondes are smarter, it does indicate to me that they are clearly not dumber," he writes.

I don't doubt his good intention to dispel a myth that leads to prejudice and stereotypes. What I worry about is how this study — and the coverage of it — might be replacing one dumb myth with another.