Gene Found That May Affect IQ in Males

Chowser writes to tell us the AZStarNet is running an article stating that North Carolina scientists claim to have identified a gene that affects IQ in males. The difference is apparently quite striking, with the average IQ difference between those that had the gene and those that didn't being approximately 20 points. From the article: "However, he stressed that the IQ results in his research were based on a group average; individual males carrying the gene version had a wide range of IQ scores. While females also can carry the variation, it does not appear to affect their IQ, he said."

Comments

StdDev = 15, but it doesn't matter

[Dire Bonobo]

> anyone know offhand what the population variance for IQ is?

The standard deviation of IQ is 15 or 16 in most scales. A difference of 1.25 standard deviations is not small.

However, without knowing the frequency of the gene in the tested population, it's impossible to know if the difference is statistically significant. If the group was 50% male and 50% had the gene, it almost certainly represents a real difference; if only 5% had the gene, that's only 7-8 guys, and the "difference" is pretty likely to be random chance.

It's also worth noting that the difference could be in developmental speed rather than in level---i.e., the guys with the gene could just take longer to develop, but be just as smart by age 25, or could be associated with some other factor that is merely correlated with intelligence (such as, say, alcoholism which can lead to poverty which can lead to a less intellectually-nurturing home life).

Basically, this article gives us a sound bite with almost no useful information---shoddy reporting.