Philosophical perspectives on response shift

This paper brings a philosophical perspective to response shift research with the aim of raising new critical questions, clarifying some of the concepts employed, and providing a philosophical context within which to critically examine the assumptions that shape the field. This critical analysis aims to reveal assumptions and clarify concepts and/or definitions that undergird methodological practice and theory. We bring attention to the distinction of weak and strong evaluations, and the implications and consequences for construct validity and for designing patient-reported outcome measures (PROMs). We then consider the epistemology of PROMs, suggesting that they are better suited to a social constructivist approach than a scientific realist one. Finally, we examine the relationship between disability and response shift, arguing that in at least some cases, response shifts should not be understood as 'measurement bias'. Our analysis reveals various concerns and further questions related to the role that substantive values play in the assessment of QoL. It also draws response shift into a wider arena, with broader issues of interpretation, self-evaluation, the meaning of the 'good life', and the status and legitimacy we accord to various scientific methods.