Optimal monetary policy with non-homothetic preferences

This paper explores the optimal design of monetary policy in a multisector model where agents' preferences are non-homothetic. Non-homotheticity derives from the existence of a minimum consumption requirement for food, which households need to satisfy for subsistence. We find that the introduction of a minimum consumption requirement reduces the weight on food inflation in the optimal index that the monetary authority should target. We identify three motives for such prescription. First, non-homothetic preferences turn the stabilization of food inflation more costly, as it requires larger deviations of output from the efficient level. Second, proximity to the subsistence level turns the demand for food insensitive to monetary policy. Inflation in this sector thus becomes difficult to control. Third, non-homothetic preferences imply that households spend only a small share of any additional income on food. This means that prices in this sector have a reduced impact on aggregate consumption demand. Hence, responding to inflation in this sector becomes less relevant. Importantly, our results provide a rationale for targeting an index that excludes (or attaches a limited weight to) food inflation, a usual practice amongst central bankers.