California’s rooftop solar mandate substantially increased adoption, but evaluating a policy requires more than measuring its effect.

Our analysis suggests that expected private payoffs explain surprisingly little of the variation in rooftop solar adoption.

Engineering models can estimate how much a rooftop solar system is worth. Economists can study whether people adopt it. Our project combined both approaches.

Earlier engineering studies suggested rooftop solar would pay off on nearly all new California homes. Our project-level analysis found a more complicated story.

Between 1990 and 2019, crisis pregnancy centers in North and South Carolina grew from roughly 60 to 146, while the number of abortion providers held flat around 35. Here’s what that expansion looked like, county by county.

Studying the causal effect of crisis pregnancy centers requires solving an endogeneity problem. Here’s how a simulated instrumental variables strategy works, and Monte Carlo evidence that it recovers the true parameter.

CPC abortion reductions are pervasive across all age groups, peaking at ages 25-29. Pregnancy rates do not respond at any age, confirming substitution. Welfare concerns concentrate among teenagers, whose marginal births carry higher low-birth-weight rates.