An Evaluation of Small Area Population Estimates Produced by Component Method II, Ratio-correlation and Housing Unit Methods for 1990

Estimated population is one of the most widely used products of demographic analyses. Population estimates are difficult to complete with accuracy for small areas because small areas can grow or decline rapidly, can change directions from growth to decline or from decline to growth, or undergo substantial changes in age, sex, race/ethnicity and other demographic characteristics. As a result, it is essential any ongoing program of population estimation periodically evaluate the results of past estimates against actual census counts for the target population. Only by assessing the accuracy of past efforts, is it possible to know the nature of errors made and to take steps to improve future estimates. In this paper I present the results of the evaluation of the 1990 population estimates produced by Component Method II, Ratiocorrelation, and Housing Unit Method compared to the 1990 Census counts for 254 counties and 1,210 places in Texas. Three error measures are used to assess the accuracy of population estimates of Texas for 1990. They are the Mean Algebraic Percent Error (MALPE), the Mean Absolute Percent Error (MAPE), and the Mean Percent Absolute Difference (MPAD). The evaluation of population estimates presented here suggests that the estimates are generally adequate and show levels of error that, when compared to the 1990 Census counts, are within generally accepted ranges. They also show the expected patterns by population size and population change. Of the several methods tested, no single one produced more accurate estimates than the average of two or three methods. The assessment of the accuracy of the placelevel estimates show substantially higher levels of errors than those found for counties.