Are International Comparisons of Subjective Health Status Relevant? An Assessment Using Anchoring Vignettes,

Abstract

When, in a survey question, response items are used in different ways by respondents, the answers are said to be affected by an item bias or by a DIF (Differential Item Functioning) effect. In such a case, the responses must be corrected before they can be used to formulate comparative hypotheses on the subjective health status of subpopulations. In this paper, we present a method for detecting and correcting for DIF effects in self-assessments of subjective health. The method is based on the individuals' assessment of health status for hypothetical situations described in short vignettes. It is exemplified by detecting a possible DIF effect in the self-assessment of physical pain, according to the geographical origin of the samples from the Share 2004 survey. Correcting for this effect leads to different conclusions than the original self-assessments concerning the respective subjective health status of the Swedish and Dutch samples.Subjective Health Measurement, Differential Item Functioning, Anchoring Vignettes, International Comparisons