Challenges with Estimating U Star in Real Time

Although the concept of the natural rate of employment, NAIRU, or “U star” is used to measure the amount of slack in the labor market, it is an unobservable quantity that must be estimated using data currently available. This Commentary investigates the degree to which our estimates of U star at various points in the current business cycle have changed as real-time data have been revised and as more data points have accumulated. I find that the availability of additional data has contributed to a significant change in our estimates of U star at earlier points in the business cycle, a result that suggests we might have been underestimating the level of labor market slack during some of the recent recovery period. In retrospect, our updated estimates of U star suggest labor markets were not as tight as we thought they were then.