| The purpose of this study was to examine the convergent and divergent validity of utility elicitation methods using a multitrait multimethod (MTMM) analysis. In addition, a structural model was built, testing the relationship between individual difference variables and utility responses.; The Standard Gamble, Time Tradeoff and Visual Analog Scale were selected because they were the three most commonly used utility elicitation methods in the field of medical decision making. Three health states---Blindness, AIDS and Stroke---were chosen to serve as traits in the MTMM analysis based on their distinctness and their simplicity.; The analysis showed that the methods achieved adequate convergent validity, i.e., measures provided by different methods converged on a given health state. However, the methods failed to achieve divergent validity i.e., methods were unable to discriminate between different health states. The presence of convergence and the lack of divergence achieved by the methods lead to the conclusion that method variance is a predominant characteristic of utility elicitation further strengthening the notion that utilities might be constructed rather than elicited by these methods.; This research was the first to include individual difference variables, cited in the literature as construct-irrelevant variables, likely to affect responses to utility elicitation methods. A linear structural model was built where education, time preference, professional and physical risk were included as exogenous variables. The model achieved a good fit and showed that physical risk was positively associated with SG utilities. The model also showed that professional risk was negatively associated with SG and TTO utilities. This research highlights the need to study these sub-types of risk more closely.; The contribution of this study lies in its exploration of the convergent and divergent validity of utility elicitation methods, which had not been done in the literature before. It finds that the methods fail to achieve divergent validity. This study also examined the relationship of construct-irrelevant individual differences to utility responses and found that specific sub-types of risk are related with utility responses on specific methods. In doing so, it is hoped that this research made substantive theoretical contributions to the field of utility elicitation. |
