State and Local Population Projections

This text focuses on the methodology and analysis of state and local population projections. It describes the most commonly used data sources and application techniques within each of three classes of projection methods (cohort-component, trend extrapolation, and structural models) and covers the components of population growth, the formation of assumptions, the development of evaluation criteria, and the determinants of forecast accuracy. It considers the strengths and weaknesses of various projection methods, paying special attention to the unique problems of making projections for small areas, and closes with an examination of technological and methodological changes affecting the production of small-area population projections. The authors provide practical guidance to demographers, planners, and other analysts called on to construct state and local population projections. They use many examples and illustrations and present suggestions for dealing with special populations, unique circumstances, and inadequate or unreliable data; they also describe techniques for controlling one set of projections to another and for interpolating between two projections.They discuss the role of judgment and the importance of the political context in which projections are made and emphasize the "utility" of projections, or their usefulness for decision making in a world of competing demands and limited resources. This comprehensive book should provide readers with an understanding not only of the mechanics of commonly used population projection methods, but also of the many complex issues affecting their construction, interpretation, evaluation, and use.