Cut-point Shift and Index Shift in Self-reported Health

There is a concern that ordered responses on health questions may differ acrosspopulations or even across subgroups of a population. This reporting heterogeneity mayinvalidate group comparisons and measures of health inequality. This paper proposes a test fordifferential reporting in ordered response models which allows us to distinguish betweencut-point shift and index shift. The method is illustrated using Canadian National PopulationHealth Survey data. The McMaster Health Utility Index (HUI) is used as a more objective healthmeasure than the simple 5-point scale of self-assessed health. We find clear evidence of indexshifting and cut-point shifting for age and gender, but not for income, education or language.