THE ACCURACY OF AGE-SPECIFIC POPULATION ESTIMATES FOR SMALL AREAS IN BRITAIN

Population estimates play an important role in the allocation of resou rces at many levels of government and commerce but little is known abo ut the accuracy of age-specific population estimates. Such knowledge i s crucial, as resource allocation is often targeted at populations of particular age, and decisions need to be based on the reliability of t he estimates. This paper presents a multi-level statistical analysis o f the accuracy of age-specific population estimates made for British l ocal authorities in 1991. The aim of this work is to identify the fact ors that influence accuracy, and to investigate how these influences i nteract. Our analyses show that the following area characteristics are key factors: true population size; intercensal population change; and percentages of unemployed residents, armed forces residents, and stud ents. In addition, we find that the overall type of method used to cal culate estimates is important, and that its effect varies both with ar ea characteristics and with age-group. Local census methods are found to be generally superior, but a low-cost apportionment method, if impl emented well, may be as effective.