This paper integrates and extends the literature on research trends in economics. Differences in the research interests of graduate students and senior scholars are examined, as are dynamic changes in research agendas over time. Significant and persistent differences in the topical distributions of books and dissertations in economics are found; but even so, regression results suggest that graduate students are influenced by the distribution of current research across fields as well as employment opportunities when selecting thesis topics. Economists appear to be influenced by external events in selecting research subjects, and exhibit a life-cycle pattern in which they move from narrower specialties to broader, more historical subjects over time.
Like the scholarship in every academic profession, economic research defines the boundaries of the discipline. In Jacob Viner's famous phrase, "Economics is what economists do" (as quoted by Robbins (1981), Hansen (1991), and Heck and Zaleski (1991)). Of course, as Lionel Robbins (1981, p. 1) pointed out, Viner's quip "only shifts the question one stage further: What is it that they do? What is the object of their investigations?" This, clearly, is a positive question, inviting empirical examination. It is rather surprising, therefore, that historians of thought have paid so little attention to the subject matter of economic research, while other aspects of the professional literature have been widely investigated. Kenneth Button (1981, p. 36) observed more than two decades ago, "A major new interest has grown amongst academic economists in recent years, the study of the professional literature in economics." While this has included numerous citation rankings of individuals, departments, and journals, scarcely any of the work has investigated the topical content of the literature. Indeed, given the general consensus that economics is, as Robbins (1935, p.16) put it, the study of the allocation of "scarce means which have alternative uses", it is ironic that economists should largely neglect to study the allocation of their own research effort among alternative fields of specialization. This point is made forcefully in Henry Villard's (1966) discussion of Bronfenbrenner's (1966) study. Villard also notes (p. 555) that "what we teach is directly related to what we research", which reinforces the notion that 'what economists do' is well captured by an examination of economic research. The value of such work is suggested by Heck and Zaleski (1991, p. 27), who note that "Knowledge of research emphasis and topical trends in the literature serves a range of researcher needs, from providing a sense of where future research is likely headed to simply satisfying a general curiosity."
Due to its brevity, the existing literature can be summarized succinctly. Stigler (1965) documented changes in the distribution of articles across fields in five leading journals for six decades up to 1953. Bronfenbrenner (1966) undertook a broader examination of articles through 1963 and a more careful study of doctoral dissertations by field from 1960 through 1965. Coats (1971) then replicated these studies using a group of five premier journals similar to Stigler's set. (Stigler (1965), Coats (1971) and Laband and Wells (1998) all examined the American Economic Review, the Quarterly Journal of Economics, and the Journal of Political Economy. Stigler also included the Review of Economics and Statistics and Econometrica, whereas Coats included Economic Journal and Economica.) Two decades later, Heck and Zaleski (1991) documented trends in journal articles by field from 1969 to 1989, just prior to the reclassification system adopted by the American Economic Association (AEA) in 1991. Diamond and Haurin (1995) considered changes in the relative importance of fields from 1927 to 1988 by examining self-reported classifications of AEA members rather than publication listings. …