Population-level response shift: novel implications for research

Response shift is a change in perceived HRQL that occurs as a result of recalibration, reprioritization, or reconceptualization
of an individual respondent’s internal standards, values, or conceptualization of HRQL. In this commentary, we suggest that
response shift may also occur at the population level, triggered by causes that affect the distribution of individual-level
risk.

We illustrated the nature and consequences of potential population-level response shift with two examples: the September 11
terror attacks, and the recent denormalization of smoking.

Response shift may occur at the population-level, when a large proportion of the population experiences the shift simultaneously,
as a unit, and when the cause of the response shift is a socially significant event or trend. Such catalysts are of a qualitatively
different nature than the causes leading to health status changes among individuals, and speak to the determinants affecting
the underlying distribution of risk in the population.

We do not know if population-level causes have actually resulted in response shifts. Nonetheless, response shifts at the population-level
may be worthwhile to investigate further, both to assess the validity of research evidence based on the measurement of HRQL
in large populations, and as a desirable intermediate outcome in evaluations of population health programs.