A two-stage random-effects meta-analysis of value per statistical life estimates

We demonstrate the use of a two-stage random-effects meta-analysis estimator for synthesizing published estimates of the value per statistical life (VSL). The meta-estimation approach accommodates unbalanced panels with one or multiple observations from each independent group of primary estimates, and distinguishes between sampling and non-sampling sources of error, both within and between groups. We use a series of Monte Carlo simulation experiments to examine the performance of the meta-estimator on constructed datasets. Simulation results indicate that, when applied to datasets of modest size, the approach performs best when the within-group non-sampling error variances are constrained to be equal across groups. This allows for two levels of non-sampling errors while preserving degrees of freedom and therefore increasing statistical efficiency. Simulation results also show that the performance of the estimator compares favorably to several other commonly used meta-analysis estimators, including other two-stage estimators. We illustrate the approach by applying it to a preliminary meta-dataset comprising 88 VSL estimates assembled from 9 hedonic wage and 9 stated preference studies conducted in the U.S. and published between 1999 and 2013.