Slashdot Mirror
Firstborn Get the Brains
Dekortage writes "Eldest children have higher IQs than their siblings, according to a recent study by Norwegian researchers. The study focused on men, particularly 'on teasing out the biological effects of birth order from the effects of social status,' but indicates that the senior boy in a family (either by being firstborn, or if an elder brother died) has an average IQ two or three points higher than younger brothers. As noted in the New York Times coverage, 'Experts say it can be a tipping point for some people — the difference between a high B average and a low A, for instance... that could mean the difference between admission to an elite private college and a less exclusive public one.'"
In this study, they had 241,310 subjects. If memory serves me right, the population standard deviation is 15 points, so we have a margin or error along the order of 15 divided by the square root of 241,310, or 0.03. That is, two orders of magnitude smaller than 3 IQ points, which to you 'seems almost within the margin of error'.
Of course, the actual margin of error depends on other things, such as how many children were firstborn in the sample, how many were secondborn, etc. Still, with such a large sample, the final standard deviation should be much smaller than a single IQ point, making their conclusions statistically interesting. And, in fact, if the results were not statistically significant, they wouldn't get published very easily, and certainly not in Science.
> Well, that explains why I'm a network admin instead of the CIO.
> I also wonder if being a middle child has any effect on IQ...
Well, the article said if the first-born dies the second born's IQ jumps up. You know what you have to do...
- For the complete works of Shakespeare: cat