This dissertation aimed to examine sources of variation in developing a societal value set for health preferences using a generic preference-based measure. Three separate studies were conducted to assess the differences due to differences in the descriptive system, time, and advance directives status. The first study sought to compare and contrast EQ-5D-5L (‘5L’) and EQ-5D-3L (‘3L’) societal value sets derived from a common sample. Compared to the 3L, value sets developed using the 5L exhibit a lower ceiling effect and improved measurement properties. There was a larger range of scale for the 3L compared to 5L; however, this difference was driven by differences in preference for the most severe level of problems in Mobility for the 3L (“confined to bed”) and 5L (“unable to walk about”). The second study aimed to better understand the implications of informed preferences and examined the association between advance directives for health care and health preferences. Advance directive completion was associated with lower values, implying greater willingness to trade years of life for better health, but not an increased likelihood of valuing health states as WTD. If advance directives are an indicator of a substantial proportion of the population with “informed” preferences, it has implications not only for intensive care decision making at the individual level, but also resource allocation based on cost-utility analysis at the group level. The final study assessed whether there were time-specific differences in health preferences between 2002 and 2017, accounting for demographic changes in the society as well as study designs. Health values in 2017 were modestly higher, implying individuals in 2017 were generally less willing to trade quantity for quality of life compared to 2002. The findings suggest that the era in which values were elicited may be an important reason to consider updating societal value sets. Overall, the work reported in this dissertation advances our understanding of how societal preferences can vary and will be important for informing health technology assessment, health care resource allocation decisions, and understanding how specific groups in society value health.