Volunteer activity is work performed without monetary recompense. This article shows that volunteering is a sizeable economic activity in the United States, that volunteers have high skills and opportunity costs of time, that standard labor supply explanations of volunteering account for only a minor part of volunteer behavior, and that many volunteer only when requested to do so. This suggests that volunteering is a "conscience good or activity"-something that people feel morally obligated to do when asked, but which they would just as soon let someone else do.

This article demonstrates that state collective bargaining laws are important determinants of union and nonunion public employee compensation. State laws that provide stronger bargaining rights and ensure closure to the bargaining process increase the direct effect of police unions on compensation. Moreover, indirect threat effects on the pay of nonunion police also increase with stronger bargaining laws. In each law category investigated, nonunion police receive most of the compensation premium enjoyed by unionized police. Previous studies that have not adequately controlled for these effects of bargaining laws have therefore underestimated the full effect of public-sector unions on compensation.

This paper examines how measurement error biases longitudinal estimates of union effects. It develops numerical examples, statistical models, and econometric estimates which indicate that measurement error is a major problem in longitudinal data sets, so that longitudinal analyses do not provide the research panacea for determining the effects of unionism (or other economic forces) some have suggested. There are three major findings:

By examining the ethnic identity of authors in over 2.5 million scientific papers written by US-based authors from 1985 to 2008, we find that persons of similar ethnicity coauthor together more frequently than predicted by their proportion among authors. The greater homophily is associated with publication in lower-impact journals and with fewer citations. Meanwhile, papers with authors in more locations and with longer reference lists get published in higher-impact journals and receive more citations. These findings suggest that diversity in inputs by author ethnicity, location, and references leads to greater contributions to science as measured by impact factors and citations.

This study investigates the impact of union organization on the wages and labor practices of establishments newly organized in the 1980s. It uses a research design in which establishments are "paired" with their closest nonunion competitor. It finds that, unionism had only a modest effect on wages in the newly organized plants, which contrasts sharply with the huge union wage impact found in cross-section comparisons of union and nonunion individuals, but unionism substantially alters several personnel practices, creating grievance systems, greater seniority protection, and job bidding and posting. That newly organized establishments adopt union working conditions but grant only modest wage increases suggests that "collective voice" rather than monopoly wage gains is the key to understanding new unionism.

We augment standard log earnings equations for workers in US manufacturing with variables reflecting measured and unmeasured attributes of their employer. Using panel employee-establishment data, we find that establishment-level employment, education of coworkers, capital equipment per worker, and firm-level R&D intensity affects earnings substantially. Unobserved characteristics of employers captured by employer fixed effects also contribute to the variance of log earnings, although less than unobserved characteristics of individuals captured by individual fixed effects. The observed and unobserved measures of employers mediate the effects of individual characteristics on earnings and increase earnings inequality through sorting of workers among establishments.

This paper analyzes the role of establishments in the upward trend in dispersion of earnings that has become a central topic in economic analysis and policy debate. It decomposes changes in the variance of log earnings among individuals into the part due to changes in earnings among establishments and the part due to changes in earnings within establishments. The main finding is that much of the 1970s–2010s increase in earnings inequality results from increased dispersion of the earnings among the establishments where individuals work. Our results direct attention to the role of establishment-level pay setting and economic adjustments in earnings inequality.