In 2003 there were 8,665 transplants of deceased donor kidneys for the approximately 60,000 patients waiting for such transplants in the United States. While waiting, 3,436 patients died. There were also 6,464 kidney transplants from living donors (Scientific Registry of Transplant Recipients web site). Live donation is an option for kidneys, since healthy people have two and can remain healthy with one. While it is illegal to buy or sell organs, there have started to be kidney exchanges involving two donor–patient pairs such that each (living) donor cannot give a kidney to the intended recipient because of blood type or immunological incompatibility, but each patient can receive a kidney from the other donor. So far these have been rare: as of December 2004, only five exchanges had been performed in the 14 transplant centers in New England. One reason there have been so few kidney exchanges is that there have not been databases of incompatible patient–donor pairs. Incompatible donors were simply sent home. (Databases are now being assembled not only in New England, but also in Ohio and Baltimore.) Lainie Friedman Ross et al. (1997) discussed the possibility of exchange between incompatible patient–donor pairs. Not only have a few such two-way exchanges been performed, but two three-way exchanges (in which the donor kidney from one pair is transplanted into the patient in a second pair, whose donor kidney goes to a third pair, whose donor kidney goes to the first pair) have been performed at Johns Hopkins. There have also been a number of “list exchanges” in which an incompatible patient– donor pair makes a donation to someone on the waiting list for a cadaver kidney, in return for the patient in the pair receiving high priority for a cadaver kidney when one becomes available.

Social Capital and Contributions in a Public-Goods Experiment by Lisa R. Anderson, Jennifer M. Mellor and Jeffrey Milyo. Published in volume 94, issue 2, pages 373-376 of American Economic Review, May 2004

The Role of the Family in Immigrants' Labor-Market Activity: An Evaluation of Alternative Explanations: Comment by Francine D. Blau, Lawrence M. Kahn, Joan Y. Moriarty and Andre Portela Souza. Published in volume 93, issue 1, pages 429-447 of American Economic Review, March 2003

New Evidence on the Money's Worth of Individual Annuities by Olivia S. Mitchell, James M. Poterba, Mark J. Warshawsky and Jeffrey R. Brown. Published in volume 89, issue 5, pages 1299-1318 of American Economic Review, December 1999

The Winner's Curse and Public Information in Common Value Auctions: Reply by Colin M. Campbell, John H. Kagel and Dan Levin. Published in volume 89, issue 1, pages 325-334 of American Economic Review, March 1999

An important class of active labor market policy has received little impact evaluation: immigration barriers intended to raise wages and employment by shrinking labor supply. Theories of endogenous technical advance raise the possibility of limited or even perverse impact. We study a natural policy experiment: the exclusion of almost half a million Mexican bracero farm workers from the United States to improve farm labor market conditions. With novel labor market data we measure state-level exposure to exclusion, and model the absent changes in technology or crop mix. We fail to reject zero labor market impact, inconsistent with this model.

One long-standing hypothesis about science and engineering labor markets is that the supply of highly skilled workers is likely to be inelastic in the short run. We consider the market for computer scientists and electrical engineers (IT workers) and the evolution of wages and employment through two periods of increased demand. Relative to the boom of the 1970s, the demand shock in the 1990s generated relatively greater changes in employment and smaller changes in wages. The growth in the pool of skilled workers abroad, combined with increased immigration in high-skill fields, is central to this story.

Parental Child Care in Single-Parent, Cohabiting, and Married-Couple Families: Time-Diary Evidence from the United Kingdom by Charlene M. Kalenkoski, David C. Ribar and Leslie S. Stratton. Published in volume 95, issue 2, pages 194-198 of American Economic Review, May 2005

The present article is an attempt to resolve the controversies concerning the concept of barriers to entry. We begin by contrasting the definitions of an entry barrier proposed in the economics literature. We then introduce a classification system to clear up the existing confusion, and we employ it to assess the nature of the barriers posed by scale economies and sunk costs.

The federal tax code provides preferential treatment for the production and use of renewable energy. We report estimates of the subsidies' effects on greenhouse gases (GHG) emissions developed in a recent National Research Council (NRC) Report. Due to lack of estimates of the impact of tax provisions on GHG emissions, new modeling studies were commissioned. The studies found, at best, a small impact of subsidies in reducing GHG emissions; in some cases, emissions increased. The NRC report also identified the need to capture the complex interactions among subsidies, pre-existing regulations, and commodity markets.