IQ, race and Hispanic immigration
The point is, however, that it's exactly backward for the media to get all worked up over one study reporting a 3 point difference between demographic groups (older and younger siblings) while ignoring the dozens of studies reporting much larger differences between demographic groups, such as between whites and Hispanics -- especially because the Senate is voting on an immigration bill right now!
The best estimate I've yet seen of Hispanic-American IQs is the 2001 meta-analysis by Roth of 39 studies covering a total 5,696,519 individuals in America (aged 14 and above). It came up with an overall difference of 0.72 standard deviations in g (the "general factor" in cognitive ability) between "Anglo" whites and Hispanics. The 95% confidence range of the studies ran from .60 to .88 standard deviations, so there's not a huge amount of disagreement among the studies.
One standard deviation equals 15 IQ points, so that's a gap of 10.8 IQ points, or an IQ of 89 on the Lynn-Vanhanen scale where white Americans equal 100. That would imply the average Hispanic would fall at the 24th percentile of the white IQ distribution. This inequality gets worse at higher IQs Assuming a normal distribution, 4.8% of whites would fall above 125 IQ versus only 0.9% of Hispanics, which explains why Hispanics are given ethnic preferences in prestige college admissions.
In contrast, 105 studies of 6,246,729 individuals found an overall average white-black gap of 1.10 standard deviations, or 16.5 points. (I typically round this down to 1.0 standard deviation and 15 points). So, the white-Hispanic gap appears to be about 65% as large as the notoriously depressing white-black gap.
So, the white-Hispanic IQ gap is about what you'd guess from observing life around you with your lying eyes: not as big and deleterious as the white-black gap, but not trivial either.
If a 3 point IQ difference between brothers is worth three articles in the New York Times, you might think that an eleven point gap between whites and Hispanics would be worth, oh, say, eleven articles, especially when the immigration bill is up for debate in the Senate. But almost nobody has ever mentioned Roth's finding in the press.
IQ, birth order, and conscientiousness