To WELLBY or not to WELLBY? Measuring non-health, non-pecuniary benefits using subjective wellbeing
Summary
Open Philanthropy recognises the need to measure benefits beyond health and income. We think that subjective wellbeing is the best tool for the task. Subjective wellbeing (SWB) is measured by asking people to rate how they think or feel about their lives. We propose that the wellbeing-adjusted life year (WELLBY), the SWB equivalent of the DALY or QALY, as the obvious unit to do cost-effectiveness analyses of non-health, non-pecuniary benefits. As our previous work has shown, using WELLBYs can change funding priorities by giving more weight to improving mental health, compared to DALYs or income measures; they may reveal different priorities in other areas.
The advantages of SWB over alternatives are fourfold. (1) SWB captures and integrates the overall benefit to the individual from all of the instrumental goods provided by an intervention. This avoids the challenging problem of assigning moral weights to different goods, makes spillover effects easier to estimate, and clarifies the importance of philosophy. (2) SWB is based on self-reports by the affected individuals whereas Q/DALYs rely on flawed predictions about how good or bad we think an intervention will be for ourselves or others. (3) Using SWB will reveal previously under-captured benefits, such as it has already done for psychotherapy. (4) Measures of subjective wellbeing already exist, are easy to collect, and widely (and increasingly) used in academia and policymaking across a wide range of circumstances and populations of interest. Furthermore, subjective wellbeing measures are reliable and valid instruments and the existing evidence supports consistent use across people.
Having said that, SWB is not without its disadvantages. (1) There is little research on the comparability between SWB scales across people. (2) We don’t know where the ‘neutral point’ lies on SWB scales. (3) We’re unsure how to choose the best measure of SWB (e.g., life satisfaction or happiness) or how to convert between them. (4) There are very few cost-effectiveness analyses using WELLBYs. Fortunately, we think these issues can be resolved and we are actively working towards doing so.