Evaluating Estimates

Abstract

Population estimates are used for a wide variety of purposes. Businesses use them to develop customer profiles, identify market clusters, and determine optimal site locations. Researchers use them to study development patterns, environmental conditions, and social trends. State and local governments use them to monitor growth trends, the impact of public policies and to estimate the need for schools, roads, parks, public transportation, fire protection, and other goods and services. Producers of estimates use this information to evaluate and improve estimation methodologies. Given these widespread uses of population estimates it is essential to evaluate their error. This chapter provides such an evaluation. We start with a discussion of various statistics that can be used to measure estimate error. We illustrate these measures using 2010 estimates for counties in Washington State and then provide an overview of the empirical evidence, focusing on the effects of differences in estimation methodology, population size, and population growth rate. We conclude the first section of this chapter with a discussion on ways to account for the uncertainty in population estimates.