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Uncommon Knowledge: Test-taking and crime, infertility and divorce

Holding back the crime

Comparing students in Louisiana who barely passed to those who barely failed the exams required for advancing to ninth grade, researchers found that students who were kept back, or “retained,” were more likely to commit violent crime as young adults. “We calculate that the increase in violent crimes, driven by grade retention, implies a social cost between $2.6 million to $18.4 million” just for this sample.

Eren, O. et al., “The Effect of Grade Retention on Adult Crime: Evidence from a Test-Based Promotion Policy,” National Bureau of Economic Research (December 2018).

Family premiums

Comparing trends across states, researchers found that “on average, state infertility insurance mandates covering in vitro fertilization treatment are associated with a 10-percent reduction in the probability of divorce. This effect is most pronounced for women in their 40s, and is concentrated among women with private insurance and college degrees and women without children.”


Cintina, I. & Wu, B., “How Do State Infertility Insurance Mandates Affect Divorce?” Contemporary Economic Policy (forthcoming).

No green communion

Analysis of a national representative sample of teenagers from the years before marijuana legalization revealed that they used marijuana less frequently in counties where more of the population was Catholic — controlling for county demographics and the teenager’s religiosity, personality, grades, social network, and parental relationships. Without these controls, Catholic presence would be positively correlated with marijuana use, “because there are more carefree parents, irreligious persons, and deviant peers in Catholic-heavy counties.”

The presence of conservative Protestants was negatively correlated with marijuana use, but this didn’t hold up with controls, such that “we may conclude that unlike the Catholic moral community, the conservative Protestant moral community does not independently affect the youths’ marijuana use behavior.”

Nie, F. & Yang, X., “The Moral Community Divide: Underage Marijuana Use Across Religious Contexts,” Journal for the Scientific Study of Religion (forthcoming).


Paying for the wall

Economists modeled the impact of scrapping the North American Free Trade Agreement (without a replacement) and found that this “lowers real incomes in the large majority of sectors in all three NAFTA countries, and that average wages fall in nearly all US congressional districts, and in all Mexican states and Canadian provinces.” The impact would nevertheless be uneven, and ironically, “Trump-voting districts would experience systematically greater wage decreases,” as “places that suffer the most from NAFTA import competition are also overwhelmingly those that export to NAFTA and use NAFTA intermediates.”

Auer, R. et al., “The Economics and Politics of Revoking NAFTA,” National Bureau of Economic Research (December 2018).

Studs vs. harlots

In a survey of thousands of Americans, some were asked to think about a close friend, while others were asked to think about a mere acquaintance, whose sexual history they were familiar with. Some were asked about a male friend/acquaintance, while others were asked about a female. Women were evaluated more negatively as their number of sexual partners increased, whereas there was no such effect for men, regardless of the participant’s gender or the closeness of the relationship.

Marks, M. et al., “The Sexual Double Standard in the Real World: Evaluations of Sexually Active Friends and Acquaintances,” Social Psychology (forthcoming).

Kevin Lewis is an Ideas columnist. He can be reached at kevin.lewis.ideas@gmail.com.