We show the importance of a dynamic aggregation bias in accounting for the PPP puzzle. We prove that established time-series and panel methods substantially exaggerate the persistence of real exchange rates because of heterogeneity in the dynamics of disaggregated relative prices. When...

Using a simple model, this paper shows how a strict monetary rule exhibits characteristics similar to those of an exchange rate anchor, in terms of a lack of robustness in the presence of adverse expectations (“bad dreams”). More specifically, as an anticipated devaluation under an exchange...