A REANALYSIS OF THE PUMP-FAILURE DATA

A fit of the Poisson-gamma model to the pump-failure data quoted by Ge orge et al. (Scand. J. Statist. 20, 147-156) using maximum conjugate l ikelihood gives pump effects that agree closely with the values obtain ed from a full Bayesian model. However, the model is a poor fit, becau se the estimates of the pump effects do not look like a sample from a gamma distribution. A split of the pumps into two subgroups does give an adequate fit.