Using modified cohort change and child-woman ratios in the Hamilton–Perry forecasting method

• Published in: Journal of population research (Canberra, A.C.T.) Vol. 34; no. 3; pp. 209 - 231
• Main Authors: Tayman, Jeff, Swanson, David A.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01-09-2017; Springer Netherlands; Springer Nature B.V
• Subjects: Accuracy; Adjustment; Age groups; Census; Censuses; Children; Children & youth; Demography; Fertility; Forecasting; Horizon; Population; Population forecasting; Social Sciences; Sociology; Trends; Synthetic forecasts; Forecast evaluation; Cohort change ratios; Hamilton–Perry method
• ISSN: 1443-2447; 1835-9469
• DOI: 10.1007/s12546-017-9190-7

The Hamilton–Perry method, which uses cohort change ratios (CCR) and child-woman ratios (CWR), has gained acceptance as research has demonstrated its practical value and accuracy in forecasting population composition. Assessments of this method have been based on the usual assumption that CCRs and CWRs developed over the base period are held constant over the forecast horizon. We propose several approaches for modifying CCRs and CWRs over the forecast horizon. These alternatives are averaging and trending these ratios and a synthetic method that bases local CCRs and CWRs changes on state-level changes in CCRs and CWRs. We evaluate the errors for these alternatives against the errors holding the CCRs and CWRs constant for counties in Washington State and for census tracts in New Mexico. The evaluation suggests that averaging or trending CCRs and CWRs are not worthwhile strategies, but the synthetic method reduces errors compared to holding the ratios constant over the horizon.