Sunday, June 21, 2009

Mean IQs of the mother country and the wages of immigrants in the U.S.

I took the above table from this research article, which predicts an immigrant's wages in America based on the average IQ of his country of origin. It is based on Census data for 106,000 immigrants. The wages were adjusted for age and education, so any correlation between country IQ and wages is not to due schooling.

It turns out that the correlation is .47. That's borderline strong. Put differently, an immigrant makes an expected one percent increase in wages for each additional IQ point. That might not sound impressive but keep in mind that: 1) the prediction is not based on the guy's IQ but that of his country of origin; and 2) one's own IQ doesn't predict wages any better. Most studies find that IQ explains about 10% of the variation in wages. IQ is an important reality, not because it predicts everything perfectly, but because it predicts better than anything else, and because it is consequential for so many areas of life.

So, if want our immigrants to stay out of poverty, which countries do we want them to come from? Well, first it makes sense to look at educational levels of the immigrants, but this study wanted to identify talent above and beyond what education captures. Perhaps someone did not have good opportunities to stay in school, but has the IQ to thrive in American society. Or perhaps the school system at home educates people beyond their abilities. Keep in mind that the researchers are taking a conservative approach: of course, much of one's educational level is due to IQ.

Here are the countries of the immigrants with the highest level of ability beyond educational level: Japan, South Africa, Australia, Denmark, Norway, and Switzerland. The wages number may not look that different, but notice how they are in log form.

As for the bottom: Ghana, Honduras, Guatemala, Mexico, and Phillipines. Filipinos do better than their numbers show because they come with relatively high levels of education. But there is no potential not captured by education.

The prediction model confirms another stereotype: immigrants from smart countries succeed in the United States; those from less intelligent places struggle.

One other point. Immigrants in the sample came from 59 countries all around the world, and the IQ means of their mother countries predicted their incomes here in the U.S. with impressive accuracy. If the IQ tests given around the world were invalid because of cultural differences and just produced noise, there should be no correlation with wages. So, this study offers more empirical support for the view that IQ tests measure cognitive ability cross-nationally in a valid way.


  1. Anonymous11:02 PM

    Boarderline strong is about right. According to this chart Syrians and Jamaicans are better workers than Koreans.

  2. Right, there are some seemingly anomalous numbers, but keep in mind that that they have been adjusted for education. Syrians and Jamaicans at the same educational level as S. Koreans earn more. Affirmative action probably influences the Jamaican number.

  3. Plus, wages have not been adjusted for region, so, for example, Jamacians might make a lot because many live in NYC.

  4. IQ of the mother country correlates with other attributes of immigrant performance in the US, including:

    Using one or more welfare programs -- (.58)

    Self-employed -- .56

    Without health insurance -- (.48)

    Less than a high school education -- (.46)

    Bachelor's and beyond -- .45

    In poverty -- (.44)

  5. Anonymous8:49 PM

    Also note that Orientals were smart when they were poor-since the fifties Japanese, Koreans and coastal Chinese populations have had 100+ IQs. I think there was a study on adopted Korean-Americans and even the malnurished ones were significantly above average.

    What we need now is a more detailed intelligence profile of non-European Caucasians. Indians, Iranians, Bangladeshi etc. Our picture of how the world is doing IQ wise is really incomplete until we have more data for them.


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