Projecting Smaller Geographies with the Cohort Component Model: Methods and Utility of Clustering

Joseph Salvo, New York City Department of City Planning
Peter Lobo, New York City Department of City Planning
Adam Willett, New York City Department of City Planning

For most municipalities in the U.S., a population projection can inform decisions in a number of areas, including budget estimation, infrastructure investment, school planning, health planning and a whole host of applications related to program planning, policy formulation and program implementation. For all of these applications, age is of critical importance, making the construction of age/sex cohort component projections a preferred route. The problem is that for many places, the small size of age/sex groups precludes the creation of stable fertility, mortality and migration rates. As the size of the base for these rates gets smaller, volatility can increase dramatically, making it impossible to construct useful projections. This paper explores the use of model rates, based on a cluster analysis, for preparing cohort-component population projections for small areas.