Proposed rehabilitation research or demonstration projects: estimating target population size

In connection with developing a benefit-cost approach to evaluating proposed rehabilitation research or demonstration projects, the need to estimate the numerical size of the associated target population is explained and a process is described for making such estimates. The process consists of 7 steps: (1) delineating project objectives, (2) specifying target group(s) in operational terms, (3) determining whether satisfactory target population prevalence estimates are available, (4) in the absence of such estimates, identifying a critical parent population and establishing its prevalence, (5) identifying an accessible population, (6) enumerating the number and proportion of target group members in the accessible population, (7) calculating the estimated target population by multiplying data yielded in steps (4) and (6), adjusting for inferred biases and indicating uncertainties of estimation. Consideration is given to the kinds of data bases upon which this estimation process depends, to the feasibility of providing such estimates, and to their probable accuracy.