[bena]

15 points is right around one standard deviation.

It's not nothing, but IQ is already a little squishy. No one's IQ is a single number. But the article also goes into problems with the study and other potential issues.

Basically, they're saying there is this pattern in the data as recorded, but there are multiple confounding factors and issues with collecting the data in the first place.

[Aloisius]

Isn't the whole point of IQ that it is a single number? Or I suppose potentially two numbers if the quotient was expressed as a fraction.

[DSMan195276]

It's a single number in that if you take an IQ test one time you get one number, but that doesn't mean you'll get that exact number every single time you take an IQ test. Even ignoring more complex questions about them, your score on an IQ test will vary depending on simple things like how tired you are when you take it, so in practice there's some variance and you do not always get the same number every time you take a test.

[tptacek]

This is a deeper question than it sounds. The "point" of a modern IQ test is to identify cognitive deficits to target interventions. It's abused widely among non-practitioners as a ranking of intelligence, which it is not.

[azan_]

I think it's widely used in research as a marker of intelligence (and for good reason - correlates really well with cognitive abilities).

[tptacek]

I don't think we have to hash this out, because "marker of intelligence" and "ranking of intelligence" are not the same thing. A rank implies a reliable scale, which IQ doesn't provide.

(It's also just fine if we disagree about this --- researchers do too!)

[bena]

I mean, nothing in the human body can be truly represented by a single number.

Even height and weight change throughout the day. People are typically taller and lighter in the morning than in the evening. Weight especially is variable, it can fluctuate up to 5 to 6 pounds.