Knowledge that Transforms

We estimate a state-of-the-art DSGE model to study the natural rate of interest in the United States over the last 20 years. The natural rate is highly procyclical, and fell substantially below zero in each of the last three recessions. Although the drop was of comparable magnitude across the three recessions, the decline was considerably more persistent in the Great Recession. We discuss the usefulness and limitations, particularly due to the zero lower bound, of the natural rate for the conduct of monetary policy.

Within the federal government, official decisions are a product of both substantive judgments and institutional constraints. With respect to discounting, current practice is governed by OMB Circular A-4 and the 2010 and 2013 technical support documents of the Interagency Working Group on the Social Cost of Carbon. Reconsideration of existing judgments must be subjected to a demanding process of internal review (and potentially to external review as well). Institutional constraints, including the need to obtain consensus, can impose obstacles to efforts to rethink existing practices, especially in an area like discounting, which is at once technical and highly controversial. Both decisions costs and error costs must be considered.

We study collective decisions by time-discounting individuals choosing a common consumption stream. We show that with any heterogeneity in time preferences, utilitarian aggregation necessitates a present bias. In lab experiments three quarters of “social planners” exhibited present biases, and less than two percent were time consistent. Roughly a third of subjects acted as if they were pure utilitarians, and the rest chose as if they also had varying degrees of distributional concerns. (JEL C91, D12, D71, D72)