The economics of labor adjustment: mind the gap

We study inferences about the dynamics of labor adjustment obtained by the "gap methodology" of Caballero and Engel [1993] and Caballero, Engel and Haltiwanger [1997]. In that approach, the policy function for employment growth is assumed to depend on an unobservable gap between the target and current levels of employment. Using time series observations, these studies reject the partial adjustment model and find that aggregate employment dynamics depend on the cross-sectional distribution of employment gaps. Thus, nonlinear adjustment at the plant level appears to have aggregate implications. We argue that this conclusion is not justified: these findings of nonlinearities in time series data may reflect mismeasurement of the gaps rather than the aggregation of plant-level nonlinearities.Labor supply ; Econometric models

Mind the (approximation) gap: a robustness analysis

This note continues the discussion of the results reported by Ricardo Caballero and Eduardo Engel (1993), hereafter CE, and Ricardo Caballero, Eduardo Engel, and John Haltiwanger (1997), hereafter CEH, by responding to the results reported in Christian Bayer (2008). Russell Cooper and Jonathan Willis (2004), hereafter CW, find that the aggregate nonlinearities reported in CE and CEH may be the consequence of mismeasurement of the employment gap rather than nonlinearities in plant-level adjustment. Bayer reassesses this finding in the context of the CE model in the case where static employment gaps are observed and concludes that the CW result is not robust to alternative shock processes. We concur with Bayer's assessment that the nonlinearity finding is sensitive to the aggregate profitability shock process. We argue, however, that Bayer's finding does not imply that the mismeasurement problem goes away. Instead, the nonlinearity created by mismeasurement is directly related to the level of the aggregate shock. Once the empirical specification properly incorporates the aggregate shock, the nonlinearity test is robust to alternative shock processes and confirms the results in CW. More importantly, we demonstrate that the CW findings are robust to alternative shock processes for the natural case of unobserved gaps as examined by CE and CEH.

Coordination of expectations in the recent crisis: private actions and policy responses

Some of the events of the recent financial crisis have made clear the importance of expectations in an economy. The economic choices individuals make are often based on their expectations of what other people will do—in what economists call a “coordination game.” In such situations, changes in the beliefs of what others may do can affect the actions of individuals. A key element in such situations is that, as the collective beliefs change and individuals respond to these altered expectations, the outcome in the marketplace can change. In the recent crisis, the coordination of expectations played a key role in areas such as financial markets, the housing market, and the automobile sector. ; When the coordination of expectations results in a crisis or a panic, policymakers are the primary group with the ability to alter the expectations of individuals. By using various policy tools, policymakers can lessen the damage from the crisis. Such tools include providing guarantees and changing marketplace incentives such as interest rates and tax rates. ; Cooper and Willis develop a framework to illustrate how the coordination of expectations was instrumental in the economic and financial crisis. The framework also helps describe the actions policymakers took to limit the severity of the downturn by coordinating expectations to achieve more positive outcomes.

The Economics of Labor Adjustment: Mind the Gap

We study the inferences about labor adjustment costs obtained by the 'gap methodology' of Caballero and Engel [1993] and Caballero, Engel and Haltiwanger [1997]. In that approach, the policy function of a manufacturing plant is assumed to depend on the gap between a target and the current level of employment. Using time series observations, these studies reject the quadratic cost of adjustment model and find that aggregate employment dynamics depend on the cross sectional distribution of employment gaps. We argue that these conclusions may not be justified. Instead these findings may reflect difficulties measuring the gap. Thus it appears that the gap methodology, as currently employed, may be unable to: (i) identify the costs of labor adjustment and (ii) assess the aggregate implications of labor adjustment costs.

Euler-equation estimation for discrete choice models: a capital accumulation application

This paper studies capital adjustment at the establishment level. Our goal is to characterize capital adjustment costs, which are important for understanding both the dynamics of aggregate investment and the impact of various policies on capital accumulation. Our estimation strategy searches for parameters that minimize ex post errors in an Euler equation. This strategy is quite common in models for which adjustment occurs in each period. Here, we extend that logic to the estimation of parameters of dynamic optimization problems in which non-convexities lead to extended periods of investment inactivity. In doing so, we create a method to take into account censored observations stemming from intermittent investment. This methodology allows us to take the structural model directly to the data, avoiding time-consuming simulation-based methods. To study the effectiveness of this methodology, we first undertake several Monte Carlo exercises using data generated by the structural model. We then estimate capital adjustment costs for U.S. manufacturing establishments in two sectors.

Euler-Equation Estimation for Discrete Choice Models: A Capital Accumulation Application

This paper studies capital adjustment at the establishment level. Our goal is to characterize capital adjustment costs, which are important for understanding both the dynamics of aggregate investment and the impact of various policies on capital accumulation. Our estimation strategy searches for parameters that minimize ex post errors in an Euler equation. This strategy is quite common in models for which adjustment occurs in each period. Here, we extend that logic to the estimation of parameters of dynamic optimization problems in which non-convexities lead to extended periods of investment inactivity. In doing so, we create a method to take into account censored observations stemming from intermittent investment. This methodology allows us to take the structural model directly to the data, avoiding time-consuming simulationbased methods. To study the effectiveness of this methodology, we first undertake several Monte Carlo exercises using data generated by the structural model. We then estimate capital adjustment costs for U.S. manufacturing establishments in two sectors.

Hours and employment implications of search frictions: matching aggregate and establishment-level observations

This paper studies worker and job flows at the establishment and aggregate levels. The paper is built around a set of facts concerning the variability of unemployment and vacancies in the aggregate, the distribution of net employment growth and the comovement of hours and employment growth at the establishment level. A search model with frictions in hiring and firing is used as a framework to understand these observations. Notable features of this search model include non-convex costs of posting vacancies, establishment level profitability shocks and a contracting framework that determines the response of hours and wages to shocks. We specify and estimate the parameters of the search model using simulated method of moments to match establishment-level and aggregate observations.Employment ; Unemployment ; Hours of labor

Implications of Search Frictions: Matching Aggregate and Establishment-level Observations

This paper studies hours, employment, vacancies and unemployment at micro and macro levels. It is built around a set of facts concerning the variability of unemployment and vacancies in the aggregate and, at the establishment level, the distribution of net employment growth and the comovement of hours and employment growth. A search model with frictions in hiring and firing is used as a framework to understand these observations. Notable features of this search model include non-convex costs of posting vacancies, establishment level profitability shocks and a contracting framework that determines the response of hours and wages to shocks. The search friction creates an endogenous, cyclical adjustment cost. We specify and estimate the parameters of the search model using simulated method of moments to match establishment-level and aggregate observations. The estimated search model is able to capture both the aggregate and establishment-level facts.

Cardiac Memory-induced T-wave Inversions

Introduction: Cardiac memory refers to T-wave inversions that result when normal ventricular activation resumes following a period of abnormal ventricular activation.Case Report: We present a case of a 29-year-old man with a pacemaker who presented with new, deep symmetric T-wave inversions caused by cardiac memory.Discussion: Abnormal ventricular activation is most commonly induced by ventricular pacing but can also occur in the setting of transient left bundle branch blocks, ventricular tachycardia, and intermittent ventricular pre-excitation.Conclusion: Recognition of this phenomenon may help to reduce unnecessary admissions, cardiac testing, and cardiac catheterizations

Collective Oscillations of Vortex Lattices in Rotating Bose-Einstein Condensates

The complete low-energy collective-excitation spectrum of vortex lattices is discussed for rotating Bose-Einstein condensates (BEC) by solving the Bogoliubov-de Gennes (BdG) equation, yielding, e.g., the Tkachenko mode recently observed at JILA. The totally symmetric subset of these modes includes the transverse shear, common longitudinal, and differential longitudinal modes. We also solve the time-dependent Gross-Pitaevskii (TDGP) equation to simulate the actual JILA experiment, obtaining the Tkachenko mode and identifying a pair of breathing modes. Combining both the BdG and TDGP approaches allows one to unambiguously identify every observed mode.Comment: 5 pages, 4 figure