Optimal Monetary Policy Response to Distortionary Tax Changes

We analyze the trade-offs faced by a monetary policy authority when a value added tax rate is increased. In the short run, such an increase acts as a cost push shock from the perspective of a central bank that is concerned with stabilizing the welfare relevant output gap. We develop a New Keynesian monetary model with real wage rigidity and consider the effects that obtain under a simple interest rate rule, on the one hand, and those that obtain under an optimal monetary policy from a timeless perspective (in the terminology of Woodford, 2003). The implications for the dynamic response of the economy differ in the presence of real wage rigidity. While under a rule inflation is higher for about eight quarters, the optimal policy involves an adjustment that is about half as long, and is followed by a slight deflation. The reason is that this policy can be shown to include a commitment to target a certain price-level, which helps contain inflation expectations. We treat the tax shock as permanent, so that the central bank does not fully revert the price level to its orginal level.Nominal and real rigidities, distortionary taxation, optimal monetary policy

Does intra-firm bargaining matter for business cycle dynamics?

We analyse the implications of intra-firm bargaining for business cycle dynamics in models with large firms and search frictions. Intra-firm bargaining implies a feedback effect from the marginal revenue product to wage setting which leads firms to over-hire in order to reduce workers' bargaining position within the firm. The key to this effect are decreasing returns and/or downward-sloping demand. We show that equilibrium wages and employment are higher in steady state compared to a bargaining framework in which firms neglect this feedback. However, the effects of intra-firm bargaining on adjustment dynamics, volatility and comovement are negligible. --Strategic wage setting,search and matching frictions,business cycle propagation

On-the-job search and the cyclical dynamics of the labor market

We show how on-the-job search and the propagation of shocks to the economy are intricately linked. Rising search by employed workers in a boom amplifies the incentives of firms to post vacancies. In turn, more vacancies induce more on-the-job search. By keeping job creation costs low for firms, on-the-job search greatly amplifies shocks. In our baseline calibration, this allows the model to generate fluctuations of unemployment, vacancies, and labor productivity whose magnitudes are close to the data, and leads output to be highly autocorrelated. --Search and matching,job-to-job mobility,worker flows,Beveridge curve,business cycle,propagation

Long-run growth expectations and "global imbalances" : [January 5, 2011]

This paper examines to what extent the build-up of "global imbalances" since the mid-1990s can be explained in a purely real open-economy DSGE model in which agents’ perceptions of long-run growth are based on filtering observed changes in productivity. We show that long-run growth estimates based on filtering U.S. productivity data comove strongly with long-horizon survey expectations. By simulating the model in which agents filter data on U.S. productivity growth, we closely match the U.S. current account evolution. Moreover, with household preferences that control the wealth effect on labor supply, we can generate output movements in line with the data. JEL Classification: E13, E32, D83, O4

On-the-job search and the cyclical dynamics of the labor market

We show how on-the-job search and the propagation of shocks to the economy are intricately linked. Rising search by employed workers in a boom amplifies the incentives of firms to post vacancies. In turn, more vacancies increases job search. By keeping job creation costs low for firms, on-the-job search greatly amplifies shocks. In our baseline calibration, this allows the model to generate fluctuations of unemployment, vacancies, and labor productivity whose magnitudes are close to the data, and leads output to be highly autocorrelated. JEL Classification: E21, E32, J64business cycle, job-to-job mobility, propagation, Search and matching, worker flows Beveridge curve

Long-run growth expectations and 'global imbalances'

This paper examines to what extent the build-up of 'global imbalances' since the mid-1990s can be explained in a purely real open-economy DSGE model in which agents' perceptions of long-run growth are based on filtering observed changes in productivity. We show that long-run growth estimates based on filtering U.S. productivity data comove strongly with long-horizon survey expectations. By simulating the model in which agents filter data on U.S. productivity growth, we closely match the U.S. current account evolution. Moreover, with household preferences that control the wealth effect on labor supply, we can generate output movements in line with the data. --open economy DSGE models,trend growth,Kalman filter,real-time data,news and business cycles,current account

Optimal redundancy against disjoint vulnerabilities in networks

Redundancy is commonly used to guarantee continued functionality in networked systems. However, often many nodes are vulnerable to the same failure or adversary. A "backup" path is not sufficient if both paths depend on nodes which share a vulnerability.For example, if two nodes of the Internet cannot be connected without using routers belonging to a given untrusted entity, then all of their communication-regardless of the specific paths utilized-will be intercepted by the controlling entity.In this and many other cases, the vulnerabilities affecting the network are disjoint: each node has exactly one vulnerability but the same vulnerability can affect many nodes. To discover optimal redundancy in this scenario, we describe each vulnerability as a color and develop a "color-avoiding percolation" which uncovers a hidden color-avoiding connectivity. We present algorithms for color-avoiding percolation of general networks and an analytic theory for random graphs with uniformly distributed colors including critical phenomena. We demonstrate our theory by uncovering the hidden color-avoiding connectivity of the Internet. We find that less well-connected countries are more likely able to communicate securely through optimally redundant paths than highly connected countries like the US. Our results reveal a new layer of hidden structure in complex systems and can enhance security and robustness through optimal redundancy in a wide range of systems including biological, economic and communications networks.Comment: 15 page