Okun's Law and Productivity Innovations
重新审视了奥肯定律的传统观点，即周期性生产率波动是需求驱动产出周期的副产品，并批评了真实商业周期模型中将生产率冲击视为外生且独立于总需求的做法。
A long tradition in macroeconomics dating back to Arthur Okun (1965) and Walter Oi (1962) regards cyclical productivity fluctuations as an artifact, a residual generated from the incomplete and lagged response of employment and labor hours to demand-driven fluctuations in real output. In Okun’s version a one percent decline in output relative to trend is divided up into a reduction of 1 ⁄3 point in productivity and 2 ⁄3 point in aggregate hours. The latter is further subdivided into a reduction of 1 ⁄3 point in the employment rate, with the remaining adjustment taking the form of lower hours per employee and in the labor force participation rate (hereafter LFPR). Yet this tradition of regarding cyclical productivity fluctuations as a byproduct of demand-driven output cycles has been almost forgotten over the past three decades as a result of widespread adoption of the real business cycle (RBC) model in which productivity shocks are treated as exogenous, as unexplained, as unrelated to aggregate demand, and as the sole driver of business cycles. Even in the more enlightened modern macro work on Dynamic Stochastic General Equilibrium Models, aggregate demand and sticky prices have reappeared, but most recent papers still include an autonomous “technology shock” as one of several causes of short-term business cycle fluctuations. Revisiting and Rethinking the Business CyCle †