Jeremy B. Rudd

Can Rational Expectations Sticky-Price Models Explain Inflation Dynamics

Recent years have seen an important trend in macroeconomic research towards analysing business cycles and stabilization policy in the context of models that incorporate both nominal rigidities and optimising agents with rational expectations. The canonical specification for the behaviour of inflation in these sticky-price rational expectations models (which is known as the new-Keynesian Phillips curve) is often criticized on the grounds that it fails to account for the dependence of inflation on its own lags. In response, many recent studies have employed a “hybrid” sticky-price specification in which inflation depends on a weighted average of lagged and expected future values of itself, in addition to a driving variable such as the output gap. In this paper, we consider some simple tests of the hybrid model that are derived from the models closed-form solution. Our results suggest that the hybrid model provides a poor description of empirical inflation dynamics, and that there is little evidence of the type of rational forward-looking behavior implied by the model.

Does Labor's Share Drive Inflation?

A number of researchers have recently argued that the new-Keynesian Phillips curve matches the empirical behavior of inflation well when the labor income share is used as a driving variable, but fits poorly when deterministically detrended output is used. The theoretical motivation for these results rests on the idea that the output gap—the deviation between actual and potential output—is better captured by the labor income share, in turn implying that central banks should raise interest rates in response to increases in this variable. We show that the empirical evidence generally suggests that the labor share version of the new-Keynesian Phillips curve is a very poor model of price inflation. We conclude that there is little reason to view the labor income share as a good measure of the output gap, or as an appropriate variable for incorporation in a monetary policy rule.

On the Relationships between Real Consumption, Income, and Wealth

The existence of durable goods implies that the welfare flow from consumption cannot be directly associated with total consumption expenditures. As a result, tests of standard theories of consumption (such as the Permanent Income Hypothesis, or PIH) typically focus on nondurable goods and services. Specifically, these studies generally relate real consumption of nondurable goods and services to measures of real income and wealth, where the latter are deflated by a price index for total consumption expenditures. This paper demonstrates that this procedure is only valid under the assumption that real consumption of nondurables and services is a constant multiple of aggregate real consumption outlays - an assumption that represents a very poor description of U.S. data. The paper develops an alternative approach that is based on the observation that the ratio of these series has historically been stable in nominal terms, and uses this approach to examine two basic predictions of the PIH. We obtain significantly different results relative to the traditional approach.

Empirical Evidence on Human Capital Spillovers

This paper examines whether the average level of human capital in a region affects the earnings of an individual residing in that region in a manner that is external to the individuals own human capital. I find little evidence of an external effect of human capital, which suggests that human capital spillovers of the form postulated by the new growth literature are unlikely to matter much in practice.

Taxation and the Taylor Principle

A nominal tax system is added to a sticky-price monetary business cycle model. When nominal interest income is taxed, the coefficient on inflation in a Taylor-type monetary policy rule must be significantly larger than one in order for the model economy to have a determinate rational-expectations equilibrium. When effective tax rates are raised by inflation, the stability of the economys equilibrium can be adversely affected. Finally, when depreciation is treated as a charge against taxable income, an even larger weight on inflation is required in the Taylor rule in order to obtain a determinate and stable equilibrium.

A Note on the Cointegration of Consumption, Income, and Wealth

Lettau and Ludvigson (2001) argue that a log-linearized approximation to an aggregate budget constraint predicts that log consumption, assets, and labor income will be cointegrated. They conclude that this cointegrating relationship is present in U.S. data, and that the estimated cointegrating residual forecasts future asset growth. This note examines whether the cointegrating relationship suggested by Lettau and Ludvigsons theoretical framework actually exists. We demonstrate that we cannot reject the hypothesis that cointegration is absent from the data once we employ measures of consumption, assets, and labor income that are jointly consistent with an underlying budget constraint. By contrast, Lettau and Ludvigson use a set of variables that do not belong together in an aggregate budget constraint, thereby testing a cointegrating relationship that is not implied by their theory.

Does the Labor Share of Income Drive Inflation

Woodford (2001) has presented evidence that the new-Keynesian Phillips curve fits the empirical behavior of inflation well when the labor income share is used as a driving variable, but fits poorly when deterministically detrended output is used. He concludes that the output gap - the deviation between actual and potential output - is better captured by the labor income share, in turn implying that central banks should raise interest rates in response to increases in the labor share. We show that the empirical evidence generally suggests that the labor share version of the new-Keynesian Phillips curve is a very poor model of price inflation. We conclude that there is little reason to view the labor income share as a good measure of the output gap, or as an appropriate variable for incorporation in a monetary policy rule.

Assessing the Productivity of Public Capital with a Locational Equilibrium Model

This paper employs Robacks locational-equilibrium model of public-goods pricing, cross-sectional data from the Census of Population and Housing, and SMSA-level estimates of public capital stocks in order to examine the productive contribution of public capital. I find that public capital has a small positive impact on private output.

Real-time properties of the Federal Reserve's output gap

This note considers the reliability of Federal Reserve Board staff estimates of the output gap after the mid-1990s, and examines the usefulness of these estimates for inflation forecasting. Over this period, we find that the Federal Reserves output gap is more reliably estimated in real time than previous studies have documented for earlier periods and alternative estimation techniques. In contrast to previous work, we also find no deterioration in forecast performance when inflation projections are conditioned on real-time estimates of the output gap.

General-Equilibrium Effects of Investment Tax Incentives

This paper develops a new-Keynesian model with nominal depreciation allowances to consider the effects of temporary tax-based investment incentives on capital spending and real activity. In particular, we investigate the effects of a temporary expensing allowance on investment in partial and general equilibrium and challenge the conventional view, advanced by Auerbach and Summers (1979) and Judd (1985), that partial-equilibrium analyses overstate the calculated impact of such policies. We also explore two additional questions. First, we investigate a claim noted by Auerbach and Summers and analyzed by Christiano (1984) that such incentives can be destabilizing. Second, we consider the relative impact of two types of tax-based investment incentives: a temporary partial-expensing allowance and a temporary reduction in capital taxes.