Introduction

Over the past decade the measurement of comparative performance has become a dominant feature of health care systems across the world (Smith, 2002). Interest is apparent at every level, ranging from the performance of individual clinicians, providers and health plans, right up to the level of entire health systems. The ultimate rationale for collecting, analysing and publishing information on relative performance is to bring about performance improvement. However, the mechanism by which this works will vary, depending on the context within which health care systems operate. For example, market-orientated systems rely to a greater extent on the operation of competitive pressures from consumers, who may use comparative information when making choices about their health care insurers or providers (Porter and Teisberg, 2004). In public health systems, the publication of comparative performance information may form the basis for regulatory intervention.

It is widely acknowledged that health care performance is multidimensional. Policy makers and the public have a legitimate interest in a wide range of aspects of performance, such as efficiency, the quality of the health care process, accessibility, clinical outcomes and responsiveness (Institute of Medicine, 2001). There is now a plethora of information available for the measurement of relative performance, and interpreting such data is therefore becoming increasingly complex. One widely adopted approach to summarizing the information contained in disparate indicators of health care performance is to create a single composite measure.