Traditional structural models cannot distinguish whether changes in activity are a function of altered expectations today or lagged responses to past plans. Polynomial-adjustment-cost (PAC) models remove this ambiguity by explicitly separating observed dynamic behaviour into movements that have...

In this paper, the authors use polynomial adjustment cost (PAC) models to analyze and forecast the main components of the U.S. trade sector. For instance, they model and measure the elasticities of imports and exports to changes in the exchange rate and income. PAC models provide a theoretical...