Posted on March 2, 2011

The PISA Rankings and the Role of Schools in Student Performance on Standardized Tests

Richard Posner, Becker-Posner Blog, January 2, 2011

International comparisons are tricky, as Becker points out, but the PISA (Programme for International Student Assessment), which tests 15-year-olds for proficiency in reading, math, and science by well designed standard tests conducted in thousands of schools all over the world, is a careful and responsible program, the results of which deserve to be taken seriously. The latest results (which are for 2009) reveal among other things that although the United States spends more money per student on secondary school education than any other country except Switzerland and Austria, Americans’ performance on the PISA tests is mediocre. In the latest tests Americans ranked 17 in reading, 24 in science, and 30 in math. 15-year-old kids in East Asian nations (including Australia and New Zealand), along with Finland, Switzerland, the Netherlands, Belgium, and Canada, outperform the United States in all three subjects. Since 2000, when the PISA tests were first given, the United States has fallen in rank in reading and science, and is unchanged in math.

{snip} Schooling is only one, though doubtless an important, input into performance on the PISA tests. Another is IQ. There have been some efforts to compare IQ across countries, notably by Richard Lynn and Tatu Vanhanen; see their 2006 book IQ and Global Inequality. Their results cannot be regarded as definitive, given significant limitations in the data, but they are suggestive. The authors find that the East Asian countries, which generally rank highest on the PISA tests (including reading–not just math and sciene), have the highest average IQs; the average IQ of Americans is lower because of our large black and Hispanic populations, which have lower average IQs than whites and Asians.

IQ is understood to reflect both genetic endowment and environmental factors, particularly factors operative very early in a child’s life, including prenatal care, maternal health, the educational level of the parents, family stability, and poverty (all these are correlated, and could of course reflect low IQs of parents as well as causing low IQs in their children). The case for very early intervention in children’s development, powerfully urged by the distinguished University of Chicago economist James Heckman, can be understood as an effort to lift IQs in the black and Hispanic communities and by doing so improve the educational performance of black and Hispanic children, including performance on the PISA tests. It is true that Heckman emphasizes noncognitive skills that facilitate learning, but these skills could also increase performance on IQ tests, indicating a positive effect on IQ.


If IQ is playing a significant role in America’s mediocre showing on the PISA tests, improvements in secondary school education are unlikely to have dramatic effects. The white and Asian kids in American schools are already doing fine, for the most part; the black and Hispanic kids may not do much better until their early childhood environment is improved to the point at which black and Hispanic IQs are raised significantly.


This observation is especially pertinent to another finding in the PISA report, which is that poor kids do better in a school that has mostly middle-class kids. Our education system, both public and private, tends as a practical matter to be segregated according to family income and social class. {snip}

Becker points out that despite the imperfections of its educational system, America remains preeminent in innovation. This is important but it appears to be due in part to the nation’s attractiveness to immigrants. Many of our innovators are foreign born; increasingly they are Asian. The United States, as a result of generous immigration policies in the nineteenth and early twentieth centuries, also has the largest Jewish population in the world–larger than Israel’s, and a higher percentage of American Jews are Ashkenazi–that is, descendants of European Jewish immigrants. This is significant because Ashkenazi Jews have a significantly higher average IQ than other Americans, including (though the margin is small) East Asians, and, as important, a very strong cultural orientation toward high achievement in business, science, and intellectual fields generally. From the standpoint of innovation, a wide distribution of IQs is more important than the average IQ, because most innovations will come from persons with an above-average IQ, and in scientific and other technical fields from persons with a way-above-average IQ. Moreover, because of the bell shape (normal distribution) of IQ across persons, a higher average IQ translates into a much longer upper tail–the part of the distribution that contains the highest IQs.