We assess whether samples of respondents drawn from large internet consumer panels are representative of the underlying population. We model the attrition/selection process for a major consumer panel maintained by Knowledge Networks, Inc (KN). Starting from KN’s over 525,000 random-digitdialed (RDD) panel-recruitment telephone contact attempts, and ending with a sample of respondents to an actual online survey, we span all junctures at which systematic selection could occur.
Individuals’ demands for programs targeting a particular illness are higher when there is a history of that illness and when subjective risks are higher. A history of other illnesses and greater other-illness subjective risks decrease demand. These comorbidity effects operate through the marginal utilities of both (i) adverse health states and (ii) income.
We develop and test an empirical model of individuals' intertemporal demands for programs to mitigate health risks over the remaining years of their lives. We find qualified support for the Erhlich (2000) life-cycle model, which predicts that individuals expect to derive increasing marginal utility from reducing health risks that come to bear later in their lives. However, we also find that as individuals age, there appears to be a systematic downward shift in their anticipated schedule of marginal utility for risk reduction at future ages. Our model improves upon earlier work by differentiating between the respondent's current age and the future ages at which they would experience adverse health states.