15Appendix A presents a model that abstracts from idiosyncratic income risk (essentially, setting  2    2
σψ = σθ = 0  ), and which produces results similar to those of our ‘realistic’ models. The simplification enables general equilibrium analysis at a small fraction of the computational cost. However, it is neither a representative agent model – the distribution of beliefs must be tracked – nor a respectable heterogeneous agents model, which may reduce its appeal to both audiences.