Zone Design in Public Health Policy

One of the most advanced tools for the spatial aggregation of areal units is zone design [1,2]. Zone design can be used to aggregate A areal units through specific criteria such as contiguity, homogeneity, or similarity into Z zones, where Z < A. However, it is important to have in mind that when data for such small areas are grouped into larger social units, the modifiable areal unit problem is present [3]. Zone design has so far been concerned with optimizing the performance of a function, producing valuable results for planning and policy in various research contexts, but not in health administration. This chapter seeks to address the research gap by developing a zone design tool specifically for public health policy. The chapter consists of three main sections. The first section describes the structure of the U.K. National Health System, focusing on England and Wales. The second section introduces the reader to basic aggregation issues and presents the principles of the zone design tool. The final section applies zone design tools in order to produce geographies with populations likely to experience similar health care needs. A comparison of Limiting Long Term Illness (LLTI) for zones in England and Wales with the abolished District Health Authorities by the Health Authorities Act 1995 is presented. In this approach, roughly 10,000 wards in England and Wales have been aggregated into 195 zones (following the 195 District Health Authorities) to create homogeneous zones in terms of LLTI. Two different objective functions have been developed in order to target two important geographical aspects. The first function builds compact zones using the LLTI variable, while the second function produces homogeneous zones, also using the LLTI variable. The comparison of these two zonations with the abolished Health Authorities provides useful insights and supports the case for a zone design approach to health administration policy in the concluding section.