The commentary paper by Rapkin and Schwartz (R&S) is about “IT” [
1]. Specifically, what is IT in the context of response shift? And can “appraisal” be a unifying approach to IT? In order to have a good representation of IT, one must also have a good representation of what is not IT. The discussion of the response shift IT is reminiscent of the discussion on frailty, difficult to define, but “I know it when I see it” [
2]. Most definitions of constructs measured by patient-reported outcomes (PROs) are clear about what is IT. However, when it comes to measuring IT, items sometimes creep in that cause IT, predict IT, modify IT, or are a consequence of IT, but in fact are not IT. In this commentary, I raise the questions as to whether appraisal is IT (response shift), a method of measuring IT, or a method of explaining IT. If appraisal is IT, then response shifts are changes in the cognitive processes that are used to arrive at a rating on a PRO. If appraisal is a measure of IT, then appraisal would be like the then-test, not IT but a measure of IT, although with fewer limitations than the then-test. If appraisal is a method of explaining IT then in a regression model of IT, appraisal would explain an important amount of variance in IT. R&S consider that appraisal is a way of operationalizing IT encompassing both measurement and explanation of IT, but not IT. …
