Abstract: In recent years New Keynesian models have become the dominant framework in macroeconomics for the study of monetary policy and business cycle fluctuations. In this class of models it is typically assumed that labor is purchased in a rental spot market. The effect of modeling labor markets in a more realistic way has been an understudied topic in the literature. This dissertation explores how the introduction of frictions in labor markets helps solve some of the puzzles faced by New Keynesian models. In the first chapter, I extend the standard New Keynesian model by incorporating labor adjustment costs and overtime work. I show that labor frictions help reconcile the frequent price changes found in the microdata with the degree of sluggishness in inflation at the macro level. The introduction of labor frictions affects the dynamic behavior of economic variables (particularly employment and inflation) and implies that firm's marginal costs should be measured in overtime costs. Marginal costs measured in overtime hours are procyclical and are predicted by inflation as suggested by theory. In the second chapter, I make use of a Bayesian likelihood approach to estimate a DSGE of the US economy using macro-economic time series. The estimated model is an extended version of the New Keynesian model with overtime labor developed in the first chapter. I show that the model does not need a high degree of price stickiness at the firm level in order to account for inflation dynamics and that it yields positive employment responses to productivity shocks. In the third chapter, the New Keynesian Phillips Curve is estimated with a marginal cost measure corrected for labor adjustment costs across different countries. I find that the labor share is a statistically significant determinant of inflation in regressions using the present value of the labor share but not in GMM regressions (in most cases). I then relate the estimates on the labor adjustment costs coefficients to measures of employment protection legislation.

We construct a utility-based model of fluctuations, with nominal rigidities and unemployment, and draw its implications for the unemployment-inflation trade- off and for the conduct of monetary policy. We proceed in two steps. We first leave nominal rigidities aside. We show that, under a standard utility specification, productivity shocks have no effect on unemployment in the constrained efficient allocation. We then focus on the implications of alternative real wage setting mechanisms for fluctuations in un- employment. We show the role of labor market frictions and real wage rigidities in determining the effects of productivity shocks on unemployment. We then introduce nominal rigidities in the form of staggered price setting by firms. We derive the relation between inflation and unemployment and discuss how it is influenced by the presence of labor market frictions and real wage rigidities. We show the nature of the tradeoff between inflation and unemployment stabilization, and its dependence on labor market characteristics. We draw the implications for optimal monetary policy.

A new approach for introducing unemployment into the New Keynesian framework. The past fifteen years have witnessed the rise of the New Keynesian model as a framework of reference for the analysis of fluctuations and stabilization policies. That framework, which combines the rigor and internal consistency of dynamic general equilibrium models with such typically Keynesian assumptions as monopolistic competition and nominal rigidities, makes possible a meaningful, welfare-based analysis of the effects of monetary policy rules. But the conspicuous absence of unemployment from the standard New Keynesian model has given rise to both criticism and attempts to rectify this anomaly. In this book, Jordi Galí, one of the major contributors to the New Keynesian literature, offers a new approach to introducing unemployment into that framework. Galí's approach involves a reinterpretation of the labor market in the standard New Keynesian model with staggered wage setting (rather than a modification or extension of the model, as has been proposed by others). The resulting framework preserves the convenience of the representative household paradigm and allows one to determine the equilibrium levels of employment, the labor force, and hence the unemployment rate conditional on the monetary policy in place. Galí develops the basic model, embedding it in a standard New Keynesian framework with staggered price and wage setting; revisits the relationship between economic fluctuations and efficiency through the lens of the new model, developing a measure of the output gap; and analyzes the relation between unemployment and the design of monetary policy.

We develop a utility based model of fluctuations, with nominal rigidities, and unemployment. In doing so, we combine two strands of research: the New Keynesian model with its focus on nominal rigidities, and the Diamond-Mortensen-Pissarides model, with its focus on labor market frictions and unemployment. In developing this model, we proceed in two steps. We first leave nominal rigidities aside. We show that, under a standard utility specification, productivity shocks have no effect on unemployment in the constrained efficient allocation. We then focus on the implications of alternative real wage setting mechanisms for fluctuations in unemployment. We then introduce nominal rigidities in the form of staggered price setting by firms. We derive the relation between inflation and unemployment and discuss how it is influenced by the presence of real wage rigidities. We show the nature of the tradeoff between inflation and unemployment stabilization, and we draw the implications for optimal monetary policy. Keywords: new Keynesian model, labor market frictions, search model, unemployment, sticky prices, real wage rigidities. JEL Classifications: E32, E50.

We construct a utility-based model of fluctuations, with nominal rigidities and unemployment, and draw its implications for the unemployment-inflation tradeoff and for the conduct of monetary policy.lt;brgt;lt;brgt;We proceed in two steps. We first leave nominal rigidities aside. We show that, under a standard utility specification, productivity shocks have no effect on unemployment in the constrained efficient allocation. We then focus on the implications of alternative real wage setting mechanisms for fluctuations in unemployment. We show the role of labor market frictions and real wage rigidities in determining the effects of productivity shocks on unemployment.lt;brgt;lt;brgt;We then introduce nominal rigidities in the form of staggered price setting by firms. We derive the relation between inflation and unemployment and discuss how it is influenced by the presence of labor market frictions and real wage rigidities. We show the nature of the tradeoff between inflation and unemployment stabilization, and its dependence on labor market characteristics. We draw the implications for optimal monetary policy.

We construct a utility-based model of fluctuations, with nominal rigidities and unemployment, and draw its implications for the unemployment-inflation tradeoff and for the conduct of monetary policy. We proceed in two steps. We first leave nominal rigidities aside. We show that, under a standard utility specification, productivity shocks have no effect on unemployment in the constrained efficient allocation. We then focus on the implications of alternative real wage setting mechanisms for fluctuations in unemployment. We show the role of labor market frictions and real wage rigidities in determining the effects of productivity shocks on unemployment. We then introduce nominal rigidities in the form of staggered price setting by firms. We derive the relation between inflation and unemployment and discuss how it is influenced by the presence of labor market frictions and real wage rigidities. We show the nature of the tradeoff between inflation and unemployment stabilization, and its dependence on labor market characteristics. We draw the implications for optimal monetary policy.

This paper presents new empirical evidence on the cyclical behavior of US unemployment that poses a challenge to standard search and matching models. The correlation between cyclical unemployment and the cyclical component of labor productivity switched sign in the mid 80s: from negative it became positive, while standard search models imply a negative correlation. I argue that the inconsistency arises because search models do not allow output to be demand determined in the short run, and I present a search model with nominal rigidities that can rationalize the empirical findings. In addition, I show that the interaction of hiring frictions and nominal frictions can generate a new propagation mechanism absent in standard new-Keynesian models.