Cognitive approaches to summary measurement: its application to the measurement of diversity in health-related quality of life assessments.

This paper describes elements of a cognitive approach to summary measurement, as it is applied to health-related quality of life (HRQOL) assessment. A summary measure, by its very nature, represents, but does not reproduce, some body of information. As a consequence, how a summary measure is formulated becomes a critical determinant of its usefulness. In most cases, formal (arithmetic or investigator-based) methods are used. However, it was also noted that a person ordinarily summarizes the information they receive. Qualitative analytic techniques (e.g., cognitive interviewing methods) can provide insight into the cognitive processes underlying such summary formation. These cognitive processes, formulated as algorithms, would also be expected to vary as a function of different groups of respondents and settings. Finding a common denominator, a common algorithm, would provide a consensus summary measure amongst diverse groups whose HRQOL is being assessed.