In this paper we present a simple theory-based measure of the variations in aggregate economic efficiency: the gap between the marginal product of labor and the household’s consumption/leisure tradeoff. We show that this indicator corresponds to the inverse of the markup of price over social...

I discuss several lessons regarding the design and conduct of monetary policy that have emerged out of the New Keynesian research program. Those lessons include the bene.ts of price stability, the gains from commitment about future policies, the importance of nat- ural variables as benchmarks...