HOUSEHOLD AND LIVING ARRANGEMENTS PROJECTIONS AT THE SUB-NATIONAL LEVEL: AN EXTENDED COHORT-COMPONENT APPROACH

This paper presents the core methodological ideas, empirical assessments and applications of extended cohort-component approach (known as ProFamy model) to simultaneously project households, living arrangements and population age structure/sizes at sub-national level. Comparisons of projections from 1990 to 2000 using this approach with census counts in 2000 for each of the 50 states and DC show that 68.0, 17.0, 11.2, and 3.8 percent of absolute percent errors are <3.0%, 3.0-4.99%, 5.0-9.99% and 10.0%, respectively. Another analysis compares average forecast errors between extended cohort-component approach and still-widely-used classic headship-rate method, by projecting number-of-bedrooms-specific housing demands from 1990 to 2000 and then comparing with census counts in 2000 for each of the 50 states and DC. The results demonstrate that, as compared to extended cohort-component approach, headship-rate method produces substantially more serious forecast errors. Illustrative projections from 2000 to 2050 for each of the 50 states, DC, six counties of Southern-California, and Minneapolis-St. Paul Metropolitan Area are reported. Among many interesting outcomes of projections with medium, low and high bounds, the aging of American households over the next few decades across all states/areas is particularly striking. Finally, the