The stability and validity of quality of life measures

Effective social indicators must be stable when individual or societal characteristics are unchanged and dynamic when circumstances alter. Highly reliable measures may be poor indicators because they are insensitive to change. Little evidence is available on the sensitivity or validity of objective and subjective indicators. A lack of panel data has restricted the assessment of the stability of subjective measures. This paper examines longitudinal data on a representative sample of 2162 Canadians interviewed in 1977 and again in 1979. Test-retest correlations of approximately 0.50 were obtained for satisfaction and self-anchoring ladder measures among respondents who reported no significant changes in their lives during the past two years. Correlations were substantially lower, as expected, for those reporting life changes. Comparisons of the absolute values of these subjective indicators show that very little change in quality of life measures occurs when stable circumstances are reported but the indicators rise or fall significantly when situations change with downward adjustments being more dramatic than upward modifications. Positive and negative life events had little effect on overall evaluations of life quality. In general, these findings provide very strong evidence for the stability and validity of subjective indicators over time. These measures, with one exception, were constant in unchanging situations and sensitive to change when it occurred.