Shining the Soles of Your Shoes: Highly Detailed Small Area Projections

Stephen J. Tordella, Decision Demographics
Balkrishna Kale, State of Wisconsin
Tom E. Godfrey, Decision Demographics

The prospect of projecting 95 large and small Tennessee counties to 2020 annually by race, Hispanic origin, and single years of age demanded both well-established and seat-of-the-pants methods. The resolution of key issues on a tight schedule will be described as a guide, and precautions to, those engaging in similar work. Migration assumptions, paramount for projections, are problematic to develop and adjust throughout the projection period. Pioneer populations of immigrants in small counties presented the greatest challenge. At the state level, the qualitative assignment of total migration apparently determined Tennessee's future with a single stroke. Multiple race groups had to be developed according to client specifications. To derive all the necessary detail, very pragmatic applications of interpolation and rounding techniques across time and within age groups were needed. Small number volatility threatened to crowd out attention to major trends. In the end, pricing strategies were developed to preclude repetition.