Uncommon Knowledge

What testing doesn’t show about teachers

And other surprising insights from the social sciences

Are we the global bad guys?

Since China’s rise as an economic power, many American foreign policy observers have been concerned that China is supporting unsavory regimes, especially in Africa. But maybe we’re just projecting. A recent analysis of data on the dollar value of international arms transfers reveals that the United States has done significantly more business than China with regimes—around the world, and in Africa—that are less democratic and have worse human rights records. According to the authors, then, “what is most remarkable is that China, which has not been as bad as countries such as Russia, the Ukraine, and Belarus, has attracted so much criticism.”

de Soysa, I. & Midford, P., “Enter the Dragon! An Empirical Analysis of Chinese versus US Arms Transfers to Autocrats and Violators of Human Rights, 1989–2006,” International Studies Quarterly (December 2012).

To lure teens, raise wages

Do you have a teenager sitting at home whom you’d rather see working? Consider advocating for a higher minimum wage. An economist at the University of Miami analyzed personnel data from a large retailer with hundreds of stores nationwide—filled with young, entry-level, part-time, low-tenure, frontline workers—to see what effect the 1996 increase in the federal minimum wage had on store employment. Contrary to what standard economic theory would predict, there was no statistically significant effect on overall employment. But the effect on the employment of teenagers—the group that would seem to be most vulnerable to losing jobs as a result of a minimum-wage hike—was positive, “driven by the increased entry of teenagers into the labor market—especially younger and more affluent teenagers.”

Giuliano, L., “Minimum Wage Effects on Employment, Substitution, and the Teenage Labor Supply: Evidence from Personnel Data,” Journal of Labor Economics (January 2013).

How teachers matter

Amid the increasing trend of using student test scores to hold teachers accountable, many teachers have protested that test scores are not fair or holistic measures of their work. This position has just gotten some strong support from new research by an economist at Northwestern University. He finds that scores on cognitive tests capture only part of the value added by teachers. Indeed, teachers may do more to change students’ futures by improving their noncognitive performance: An “increase in estimated noncognitive ability in 8th grade (a weighted average of attendance, suspensions, grades, and grade progression) is associated with larger improvements in arrests, college-going, and wages than [the same relative] increase in test scores....Additional calculations suggest that teacher effects on college going and wages may be as much as three times larger than that predicted based on test scores alone. As such, more than half of teachers who would improve long run outcomes may not be identified using test scores alone.”

Jackson, K., “Non-Cognitive Ability, Test Scores, and Teacher Quality: Evidence from 9th Grade Teachers in North Carolina,” National Bureau of Economic Research (December 2012).

Recycling, the dark side


It’s better for the environment to recycle than to throw recyclable goods in the trash. However, this proposition looks less green when you factor in the law of unintended consequences. In one experiment, when asked to try out a pair of scissors, people cut up more paper if a recycling bin was available than if just a trash can was available, regardless of their environmental attitudes. In another experiment in a men’s restroom, more paper towels were used per person if a recycling bin was available than if just the normal trash receptacles were available.

Catlin, J. & Wang, Y., “Recycling Gone Bad: When the Option to Recycle Increases Resource Consumption,” Journal of Consumer Psychology (January 2013).

Bigots think inside the box

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What’s wrong with being racist? The obvious downside is for the people facing prejudice, but it turns out the racists may be doing themselves an unexpected disservice as well. In a new study, an international team of researchers found that priming beliefs about innate racial differences—by having people read about bogus scientific research substantiating such differences—made people more closed-minded and ultimately impaired their creative problem-solving.

Tadmor, C. et al., “Not Just for Stereotyping Anymore: Racial Essentialism Reduces Domain-General Creativity,” Psychological Science (forthcoming).

Kevin Lewis is an Ideas columnist. He can be reached at