Richie Rich Aces the SAT


A California high schooler takes the Scholastic Aptitude Test (SAT). 

The College Board released its data on 2012 SAT scores on Monday, and beneath the headlines (which tallied how much SAT scores have slipped as more and more students take the test) was a revealing picture of the influence of students’ household income on their performance.

The influence couldn’t be more decisive. The board measured household income in increments of $20,000—starting with students from households making $0 to $20,000 annually, then $20,000 to $40,000, all the way up to $160,000—then an increment of $40,000 ($160,000 to $200,000) and then a final category of more than $200,000. And SAT scores rose considerably at every step in the income scale. The poorest students, from households making less than $20,000 had a mean combined score of 1322 out of 2400; the next highest, 1397; then 1458, then 1497—all the way to a score of 1722 for students from households making more than $200,000. That’s a 400-point difference between our richest and poorest students.

These mournful numbers cast a harsh light on the practice, beloved by “educational reformers,” of measuring teacher performance chiefly, if not exclusively, by test scores. Test scores, the data make clear, reflect social class and economic standing far more than anything else. If our educational reformers were serious about raising test scores, and student aptitude, and the competence of the American workforce, they might turn their attention to alleviating poverty and lifting living standards for our downwardly mobile working and middle class. Blaming teachers for these test scores is a lot easier, of course, than reducing our record levels of economic inequality. Problem is, it does nothing to address the huge disparities in academic performance and aptitude. Unless they tackle our yawning gaps in income and wealth, our educational reformers won’t make a dent in the problems about which they profess to care. 


Actually, this is an example of omitted variable bias. Smarter tend to do better academically. They may earn more money. They pass on their genes to their children. So no surprise their children also do better academically.

Professor Steve Hsu, who is also involved in the BGI Cognitive Genomics Project,, posted on this issue:

"It is sometimes claimed that IQ is just a proxy for SES (Socioeconomic Status): high IQ kids are merely the beneficiaries of better home environments, and correlations between IQ and life outcomes are merely a proxy for correlations between childhood environment and outcomes. Of course, this claim does not address the significant variations in IQ within families. Does IQ have predictive power once SES is controlled for? The answer is obvious from anecdotal experience: we all know siblings who, by definition, shared the same family SES, but with different IQs and life outcomes.

Vanderbilt psychologist David Lubinski sent me a recent paper addressing this issue -- Cognitive Epidemiology: With emphasis on untangling cognitive ability and socioeconomic status, Intelligence 37 (2009) 625-633. Among the figures is the following one, based on NLSY longitudinal data (the analysis was originally done by Charles Murray). It compares life outcomes of paired siblings (one of each pair required to be in the "normal" reference range of IQ), thereby controlling for SES. As you can see, IQ has a strong impact on education, earnings and social status even after family SES is controlled for.

Similar analysis shows that the correlation between SAT scores and college grades only decreases slightly when SES is controlled for. See also related post on non-shared environmental effects.

Below is a useful SES-SAT (or SES-IQ) syllogism, well supported by the studies at the two links above.

SES does not cause SAT (weakly at most). ***
SES does not predict college success, SAT does.

Also, you still get a significant achievement gap by ethnicity.

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