Knowledge that Transforms

We provide evidence suggesting that the cross-sectional distributions of US consumption and its growth rate obey the power law in both the upper and lower tails, with exponents approximately equal to four. Consequently, high-order moments are unlikely to exist, and the generalized method of moments estimation of Euler equations that employs cross-sectional moments may be inconsistent. Through bootstrap studies, we find that the power law appears to generate spurious nonrejection of heterogeneous-agent asset pricing models in explaining the equity premium. Dividing households into age groups, we propose an estimation approach that appears less susceptible to fat tail issues.

Analyzing the savings behavior of a large sample of identical and fraternal twins, we find that genetic differences explain about 33 percent of the variation in savings propensities across individuals. Individuals are born with a persistent genetic predisposition to a specific savings behavior. Parenting contributes to the variation in savings rates among younger individuals, but its effect decays over time. The environment when growing up (e.g., parents’ wealth) moderates genetic effects. Finally, savings behavior is genetically correlated with income growth, smoking, and obesity, suggesting that the genetic component of savings behavior reflects genetic variation in time preferences or self-control.

We provide a model of conflict and mass killing decisions to identify the key variables and situations that make mass killings more likely to occur. We predict that mass killings are most likely in countries with large amounts of natural resource rents, polarization, institutional constraints regarding rent sharing, and low productivity of labor. The role of resources such as oil, gas, and diamonds and other key determinants of mass killings is confirmed by our empirical results based on country-level as well as ethnic group–level analysis.

We study a change in maternity leave entitlements in Norway. Mothers giving birth before July 1, 1977, were eligible for 12 weeks of unpaid leave, while those giving birth after that date were entitled to 4 months of paid leave and 12 months of unpaid leave. The increased time spent with the child led to a 2 percentage point decline in high school dropout rates and a 5 percent increase in wages at age 30. These effects were larger for the children of mothers who, in the absence of the reform, would have taken very low levels of unpaid leave.