Health Inequalities and Anchoring Vignettes 

 I have earlier written about using anchoring vignetttes to correct for biases in self-reported measures such as health outcomes ( here   and  here ).  One issue with self-reports is that respondents may interpret identical questions in different ways.  The idea of vignettes is use controlled scenarios to measure this bias and adjust the self-reports accordingly, so that they are informative about the actual health status. 

 An interesting application of this method is a paper by D'Uva et al ( 2006 working paper here ), who use vignettes from the  World Health Surveys  to identify and correct reporting heterogeneities in Indonesia, China and India.  Their objective is to establish whether the reporting differences affect measures of within-country inequality in several health domains (mobility, self-care etc).  They find evidence for reporting heterogeneity but also suggest that the bias is not large in their data. 

 The paper also discusses in more detail two assumptions underlying the vignette method, ``response consistency'' and ``vignette equivalence'' (also discussed in  King et al 2004 ).   


 ``Response consistency'' requires that respondents assess their own health in the same way that they assess other people's health (i.e. the vignette scenarios).  This may fail if there is strategic reporting, for example when one's reported health status could provide access to entitlement programs for which other people's health status is irrelevant.  ``Vignette equivalence'' essentially requires that the scenarios in the vignettes are perceived similarly across respondents; no systematic differences are allowed.  The authors suggest that a failure of this latter assumption may underlie findings with respect to age that are in contrast with other studies.  Elderly people might interpret the vignette scenarios differently since they are more likely to have own experiences with the described health problems. 

 I am curious whether these assumptions have been tested in detail.  This might also stimulate some thinking about what elements of self-reports we want to correct for, and whether the determinants of reporting biases are of their own interest.