We develop a social choice experiment to estimate public preferences on population ethics. Our experiment poses three within-subject treatments in which participants allocate scarce resources to determine the health-related quality-of-life, and existence, of two population groups. We combine random behavioural and random utility models to enable the estimation of participant-level preference parameters within social welfare functions. Using a sample of the UK adult population (n=115, obvs.=5,060), we find that 97.4\% of respondents are inequality averse, prioritising the worst-off at the expense of efficiently maximising overall health. The majority of participants (54.8\%) maximise total welfare, with no critical-level threshold, but, we find extensive heterogeneity in participants population preferences. We demonstrate how these preferences can be used to aid policy decisions, where difficult trade-offs emerge between equity and efficiency, average and total welfare, and population size.

Keywords: Inequality, Health, Experiment, Social Welfare, Population Ethics.
JEL Codes: C90, D63, I18.