This paper examines the relationship between gun ownership and crime. Previous research has suffered from a lack of reliable data on gun ownership. I exploit a unique data set to reliably estimate annual rates of gun ownership at both the state and the county levels during the past two decades. My findings demonstrate that changes in gun ownership are significantly positively related to changes in the hom-icide rate, with this relationship driven almost entirely by an impact of gun ownership on murders in which a gun is used. The effect of gun ownership on all other crime categories is much less marked. Recent reductions in the fraction of households owning a gun can explain one-third of the differential decline in gun homicides relative to nongun homicides since 1993. I.

Although theory on corruption is well developed, it has proven difficult to isolate corrupt behavior empirically. In this paper, we provide overwhelming statistical evidence documenting match rigging in Japanese sumo wrestling. A non-linearity in the incentive structure of promotion leads to gains from trade between wrestlers on the margin for achieving a winning record and their opponents. We show that wrestlers win a disproportionate share of the matches when they are on the margin. Collusion, rather than increased effort, appears to explain the results. Wrestlers who are victorious when needing a victory lose more often than would be expected the next time they meet that same opponent, suggesting that part of the payment for throwing a match is future payment in kind. Cheating disappears in times of high media scrutiny. In addition to collusion by individual wrestlers, there is also evidence of reciprocity agreements across stables of wrestlers, suggesting a centralized element to the match rigging.

We examine whether and to what extent consolidation in the US health insurance industry has contributed to higher employer-sponsored insurance premiums. We exploit the differential impact across local markets of a national merger of two insurers to identify the causal effect of concentration on premiums. Using data for large groups, we estimate premiums in average markets were approximately seven percentage points higher by 2007 due to increases in local concentration from 1998–2006. We also find evidence consolidation facilitates the exercise of monopsonistic power vis-à-vis physicians, leading to reductions in their absolute employment and earnings relative to other healthcare workers. JEL: G22, I13

Medicare Part D began coverage of prescription drugs in 2006. Using data from the first year of the program we found that Part D reduced pharmaceutical prices for Medicare recipients, with these effects driven by enrollees previously without drug coverage. In this paper we extend our analysis through 2009, the fourth year of the program, to investigate whether plans continued to extract price concessions in return for favorable formulary placement, or if consumer inertia or other factors caused prices to bounce back after their initial decline. We find price declines persisted through at least the third year of the program.

Using Current Population Survey and US Army administrative data, we document that between 2000 and 2010, the employment rate of Vietnam era veterans fell markedly relative to non-veterans of the same cohorts while simultaneously their enrollment increased steeply in the Veterans Disability Compensation (DC) program, which provides healthcare and transfer payments to veterans with service-connected disabilities. Thirty percent of Vietnam era Army veterans enrolled in DC in 2006 received benefits for Post-Traumatic Stress Disorder, with median annual payments of $25,500. The declining employment and rising transfer payments to Vietnam era veterans underscore the long-term private and public costs of wartime service, potentially stemming from both adverse health consequences and policies that have expanded benefits eligibility.

In 2005, as the result of a World Trade Organization mandate, India implemented a patent reform for pharmaceuticals that was intended to comply with the 1995 Trade-Related Aspects of Intellectual Property Rights (TRIPS). Exploiting variation in the timing of patent decisions, we estimate that a molecule receiving a patent experienced an average price increase of just 3–6 percent, with larger increases for more recently developed molecules and for those produced by just one firm when the patent system began. Our results also show little impact on quantities sold or on the number of pharmaceutical firms operating in the market.

To combat adverse selection, governments increasingly base payments to health plans and providers on enrollees’ scores from risk-adjustment formulae. In 2004, Medicare began to risk-adjust capitation payments to private Medicare Advantage (MA) plans to reduce selection-driven overpayments. But because the variance of medical costs increases with the predicted mean, incentivizing enrollment of individuals with higher scores can increase the scope for enrolling "overpriced" individuals with costs significantly below the formula's prediction. Indeed, after risk adjustment, MA plans enrolled individuals with higher scores but lower costs conditional on their score. We find no evidence that overpayments were on net reduced.

We examine the effect of more than 3,400 gun shows using data from Gun and Knife Show Calendar and vital statistics data from California and Texas. Considering the one month following each show and a surrounding area ranging from 80 to 2,000 square miles, we find no evidence that gun shows increase either gun homicides or suicides. The similarity of our estimates for California and Texas suggests that the much tighter California gun show regulations do not substantially reduce the number of firearms-related deaths in that state. Using incident-level crime data for Houston, Texas, we also find no evidence of an effect on other crime categories.