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In a widely influential essay, Ryder argued that to understand social change, researchers should compare cohort careers, contrasting how different cohorts change over the life cycle with respect to some outcome. Ryder, however, provided few technical details on how to actually conduct a cohort analysis. In this article, the authors develop a framework for analyzing temporally structured data grounded in the construction, comparison, and decomposition of cohort careers. The authors begin by illustrating how one can analyze age-period-cohort (APC) data by constructing graphs of cohort careers. Although a useful starting point, the major problem with this approach is that the graphs are typically of sufficient complexity that it can be difficult, if not impossible, to discern the underlying trends and patterns in the data. To provide a more useful foundation for cohort analysis, the authors therefore introduce three distinct improvements over the purely graphical approach. First, they provide a mathematical definition of a cohort career, demonstrating how the underlying parameters of interest can be estimated using a reparameterized version of the conventional APC model. The authors call this the life cycle and social change (LC-SC) model. Second, they contrast the proposed model with two alternative three-factor APC models and all logically possible two-factor models, showing that none of these other models are adequate for fully representing Ryder's ideas. Third, the authors present the article's major accomplishment: using the LC-SC model, they show how a collection of cohort careers can be decomposed into just four basic components: a curve representing an overall intracohort trend (or life cycle change); a curve representing an overall intercohort trend (or social change); a set of common cross-period temporal fluctuations that permit variability across cohort careers; and, finally, a set of terms representing cell-specific heterogeneity (or, equivalently, interactions among age, period, and/or cohort). As the authors demonstrate, these parts can be reassembled into simpler versions of cohort careers, revealing underlying trends and patterns that may not be evident otherwise. The authors illustrate this approach by analyzing trends in political party strength in the General Social Survey.

This paper examines the relationship between family career and age cohort. The family career concept originates in the work of developmental theorists such as Rodgers (1973). It is argued that the concept of the family career represents a more sophisticated approach and understanding of developmental theory than does the use of the present stage of the life cycle. The results of this research suggest that age cohort has little effect on the pattern of stages in the family career but that age cohort is moderately associated with the timing or spacing between stages.

This paper develops a design-based approach to identifying cohort effects in APC analyses. Cohort effects arise when one cohort is treated by a unique set of formative socialization experiences, which causes it to differ from other cohorts in relevant outcomes. APC analyses typically compare treated and untreated cohorts from a single population. Our approach introduces a second group-a control group, in which no unit is treated but that is otherwise similar to the first-and adapts difference-in-differences estimation to the APC framework. The approach yields two identification strategies, each based on transparent and testable assumptions. We illustrate how the method works and what is to be gained through three examples. © 2013 Elsevier Ltd.

Dept. of History, Philosophy, and Political Science. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1976 .R447. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.)--University of Windsor (Canada), 1976.

ABSTRACTAggregate data on US earnings, classified by period and by age, are decomposed into age, period and cohort effects, using the Bayesian cohort models, which were developed to overcome the identification problem in cohort analysis. The main findings, obtained by comparing college and high school graduates, are threefold. First, the age effects show a downward trend for the age group of 45–49 onwards for high school graduates but do not show any such trend for college graduates. Second, the period effects show a downward trend for high school graduates but reveal no such trend for college graduates. Third, the cohort effects are negligible for both college and high school graduates.

SummaryBangladesh represents one of the few countries in south Asia where the pace of fertility decline has been unprecedented over the last three decades. Although there has been significant reduction in fertility levels at the national level, regional variations continue to persist, especially in Sylhet and Chittagong where the total fertility rates are well above the country average. Using data from three consecutive Bangladesh Demographic and Health Surveys (BDHSs) this paper assesses how fertility patterns in Sylhet and Chittagong differ from the rest of Bangladesh through a marriage cohort analysis of the parity progression ratios, and examines the factors determining the transition rates to higher parity in these two regions. Three cohorts of women are identified: those married during 1965–1974, 1975–84 and 1985–94. The results show that the probability that a woman from the recent cohort in Sylhet or Chittagong who had a third birth will have a fourth birth is nearly twice that of her counterpart in other regions. Social characteristics such as education, occupation, religion and residence have no effect on fertility in Sylhet and Chittagong. Additional period-specific analyses using the 2007 BDHS data show that women in Sylhet are considerably more likely to have a third or fourth birth sooner than those in other divisions, especially Khulna. The findings call for specific family planning policy interventions in Sylhet and Chittagong ensuring gender equity, promoting female education and delaying entry into marriage and childbearing.