AGING AND PRODUCTIVITY AMONG ECONOMISTS

AGING AND PRODUCTIVITY AMONG ECONOMISTS Ph.D.Ph.D.Ph.D.e.g.Ph.D.ract--Economists’ productivity over

AGING AND PRODUCTIVITY AMONG ECONOMISTS Ph.D.Ph.D.Ph.D.e.g.Ph.D.ract--Economists’ productivity over their careers and as measured by publication in leading journals declines very sharply with age. There is no difference by age in the probability that an article submitted to aleading journal will be accepted. Rates of declining productivity are no greater among the very top publishers than among others, and the probability of acceptance is increasingly related to the author’s quality rather than the author’s age. It is well known that productivity declines with age in awide range of activities. Lehman (1953) suggests an early peak in productivity in avariety of scientific and artistic endeavors, and Diamond (1986) documents the pattern for several scholarly pursuits. Levin and Stephan (1992) provide clear evidence that this decline exists even after careful attempts to account for individual and cohort differences. Fair (1994) finds declines in physical ability among elite runners, as does Lydall (1968,pp. 113 passim) in physical abilities of the population generally. In this study we examine productivity declines in our own field. The main new results arise from our use of two different types of information, the equivalent of household and establishment data, to study the stone field over essentially the same period of time. Section Idiscusses the general results on aging and productivity, whereas section II presents evidence of the importance of heterogeneity. I. Declining Productivity with Age Using the American Economic Association (AEA) Directory of Members, we identified tenured economics faculty at 17 top research institutions and obtained the years of their Ph.D. degrees.[1] With the citation index of the Journal of Economic Literature we replicated portions of the curricala vitae of each of the 208 economists currently in the economics departments of those institutions who received Ph.D. degrees between 1959 and 1983.[2] To measure productivity we construct three indexes, combining papers published in refereed journals. Prior research suggests that, at least in terms of salary determination, the returns from nonreferred publications are quite low Sauer (1988), so that we ignore such publications in calculating these measures. I1 weights an article by the journal where it appears based on citations to that journal, using values generated by Laband and Piette (1994). This index distinguishes strongly among journals. For example, the Journal of Political Economy has aweight of 59.1, whereas Economic Inquiry has aweight of 7.9. In constructing I1 we use the weights associated with the decade in which the articles were published. I2 distinguishes somewhat less among journals by assigning all articles in the nine “core” journals identified by Laband and Piette avalue of 1, whereas all other journals are valued at 0.5.[3] Finally, I3 gives all papers aweight of 1. Coauthored articles were given half credit, consistent with Sauer’s (1988) findings on the economic returns to coauthorship.[4]