Mapping under-five mortality in the Wenchuan earthquake using hierarchical Bayesian modeling.

More than two years after the 2008 earthquake in Wenchuan, China, the total number of lives lost remains unclear, particularly for children under five years old. Mortality for this age group can be estimated using a variety of techniques, but sample proportion estimates may be unreliable in areas with low populations of children under five. To address this problem, we propose a hierarchical Bayesian model to map the distribution of under-five mortality in Wenchuan at the township scale. This model is based on conditional distributions for data conditioned on a spatial process and parameters to capture uncertainties usually identified as either spatially-correlated effects or heterogeneity effects. The method was adapted to obtain reliable estimates of the under-five mortality rate in townships with low under-five populations. The approach was compared to other models and, despite some limitations, was found to outperform other methods in its smoothing effect as well as in exploration of other aspects of spatial patterns.