Inventory Investment and the Empirical Phillips Curve

In this paper, we study the Calvo pricing models with finished goods inventory investment to demonstrate that the current inflation can be expressed as a function of the marginal cost of sales, not the marginal production cost, and expected future inflation. Under the assumption that the true aggregate marginal costs are not observable in actual data, we make use of equilibrium conditions for aggregate finished goods inventories to measure the time series of marginal costs, thereby leading to the construction of inflation series on the basis of the Phillips curve. Our results indicate the possibility of a successful fit of the empirical New Keynesian Phillips curve without relying on unit labor cost—a conventional measure of marginal production cost in the literature.