The BMW Model: A New Framework for Teaching Monetary Economics

Abstract: Although the IS/LM-AS/AD model is still the central tool of macroeconomic teaching in most macroeconomic textbooks, it has been criticized by several economists. Colander (1995) demonstrated that the framework is logically inconsistent, Romer (2000) showed that it is unable to deal with a monetary policy that uses the interest rate as its operating target, and Walsh criticized that it is not well suited for an analysis of inflation targeting. The authors present a framework that develops the Romer approach into a very simple but, at the same time, comprehensive macroeconomic model. In spite of its simplicity, it can carry the main insights of the New Keynesian macroeconomics to an intermediate level and deal with issues like inflation targeting, monetary policy rules, and central bank credibility.     

A note on representability of consumer's behavior

Summary. We offer an alternative approach to the study of representability of choice behavior in a competitive framework that is based on recent advances in utility theory (cf. Alcantud and Rodrí guez-Palmero (1999)). Our technique enables us to tackle this classical problem efficiently in fairly general situations, thus obtaining alternative sufficient conditions as well as different proofs and generalizations of prior results. Received: July 14, 1999; revised version: February 15, 2001     

Exogenous tax changes and interest rates: testing for Ricardian equivalence using an efficient markets model

This article tests the Ricardian theory (i.e., Barro 1974) using Mishkin’s (1981, 1982) efficient markets model of interest rates. Employing Romer and Romer’s (2010) measure exogenous tax changes, I am able to test whether the U.S. bond market reacts in a Keynesian or Ricardian manner to exogenous tax policy changes. This helps avoid the endogeneity problems associated with measuring the interest rate effects of deficits and provides a cleaner test of the pure Ricardian thought experiment. I find a significant negative relationship between tax changes and interest rates which is inconsistent with the Ricardian model and support the Keynesian crowding out framework.     

Using Romer and Romer's new measure of monetary policy shocks to identify the AD and AS shocks

This article re-examines the series of (exogenous) Federal Funds Rate (FFR) shocks created by Romer and Romer (2004) for the period 1969:01–1996:12. We hypothesize that if Romer and Romer have constructed a reasonable set of monetary policy shocks, then including them in a small Vector Autoregression (VAR) should help to identify other structural shocks that affected the United States economy during their sample period. Using a sample period of 1971:01–1996:12 we are easily able to identify both an Aggregate Demand (AD) shock and an Aggregate Supply (AS) shock without imposing any sign or long-run restrictions. We present historical decompositions that allow us to compare the relative importance of these shocks with that of the exogenous monetary policy shocks in explaining output fluctuations during the 1973–1975, 1980–1984 and 1990–1991 business cycle episodes.     

Paul Romer: Ideas,Nonrivalry, and Endogenous Growth

In 2018, Paul Romer and William Nordhaus shared the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel. Romer was recognized “for integrating technological innovations into long‐run macroeconomic analysis”. This article reviews his prize‐winning contributions. Romer, together with others, rejuvenated the field of economic growth. He developed the theory of endogenous technological change, in which the search for new ideas by profit‐maximizing entrepreneurs and researchers is at the heart of economic growth. Underlying this theory, he pinpointed that the nonrivalry of ideas is ultimately responsible for the rise in living standards over time.     

Stochastic Growth and Factor Income Risk

Abstract. This paper examines the effects of aggregate factor income risk in a tractable version of the stochastic Romer endogenous growth model. Labor supply is endogenous. The presence of labor income risk unambiguously increases savings and growth due to precautionary motives. Households not only underaccumulate but also work less along the balanced growth path of the competitive economy when compared with the Pareto-efficient allocation. The paper also discusses distributive disturbances for the case of inelastic labor supply. Here, growth effects are negative for empirically plausible correlations of the underlying shocks.     

Tax multipliers and monetary policy: Evidence from a threshold model

Romer and Romer (2010) use the narrative record to generate a time series of exogenous shocks to fiscal policy. They report a tax multiplier of 3.0. We extend their analysis and allow for nonlinearities between their shocks and the effects on output by estimating a threshold regression model. Using Hansen’s (1997) procedure, we find the best fitting threshold is changes in the federal fund rate with a delay of two quarters. Moreover, we find that the tax multiplier is approximately 4.3 if accompanied by an accommodative monetary policy and approximately 1.2 under tight monetary policy.     

Effects of exports on productivity and growth in India: an industry–based analysis

This study analyses the effects of exports on the level of output per capita using the panel estimates of an extended version of the Mankiw, Romer and Weil (The Quarterly Journal of Economics, CVII, 407-37, 1992) model, and on the total factor productivity using the time series estimators. The analysis is carried out for ten industries in the manufacturing sector in India. The results do not provide any evidence of convergence, and instead support the contrary evidence of divergence among industries. The exports do not induce convergence and instead seem to accentuate the process of divergence among industries. The study provides some evidence for the significant effects of exports on the level of output per capita and TFP in the manufacturing sector. The effects of exports on TFP are significant in half of the sample industries, while in the remaining half these are statistically insignificant.     

The economic impact of EU-enlargement: assessing the migration potential

This paper analyzes the determinants of immigration flows to Germany in a time series-cross section framework. The reduced form of a well established theoretical model is estimated for a sample of 17 sending countries and a period covering 1960 to 1994. The estimates are then used to perform out-of-sample forecasts to assess the immigration potential from the Eastern European accession candidates to Germany. These scenarios predict a moderate increase in immigration to Germany, especially for the first round accession candidates. First version received: July 1999/Final version received: July 2000     

Characterizing C2 aggregate excess demand functions

Summary. We integrate and sharpen two characterizations of aggregate excess demand functions: we obtain Mas-Colell's (1977) equilibrium invariance, and strengthen Geanakoplos' (1984) weakly concave utility functions to strictly concave ones. Our proofs modify and extend Geanakoplos' utility-construction. We note two applications: a sharper characterization of equilibrium price sets (cf. Mas-Colell (1977)), and a basis for the studies of computable economies (Richter and Wong (1996)). Received: July 29, 1996; revised version: February 20, 1997     

Two simple proofs of the feasibility of the linear tracing procedure

Summary. Theories of equilibrium selection in non-cooperative games, as well as the notion of risk dominance, depend heavily on the so-called linear tracing procedure. This is the first paper to give direct, simple proofs of the feasibility of the linear tracing procedure. The first proof utilizes a result that is related to Kakutani's fixed point theorem and that is an extension of Browder's fixed point theorem. The second proof shows that it is even possible to avoid the use of correspondences. Received: June 8, 1998; revised version: November 8, 1998     

On Lipschitz continuity of policy functions in continuous-time optimal growth models

Summary. This paper proves the C ^1,1 differentiability of the value function for continuous time concave dynamic optimization problems, under the assumption that the instantaneous utility is C ^1,1 and the initial segment of optimal solutions is interior. From this result, the Lipschitz dependence of optimal solutions on initial data and the Lipschitz continuity of the policy function are derived, by adding an assumption of strong concavity of the integrand. Received: July 29, 1996; revised version: November 25, 1997     

Reassessing the empirical validity of the human-capital augmented neoclassical growth model

We reassess Mankiw, Romer and Weil's [mrw] version of the Solow model using, as did mrw, cross-sectional data to estimate the steady-state equation governing income per capita levels. The model fails in two critical areas. First, plausible factor shares obtained by mrw are not robust to the substitution of two measures of human capital that are more precise than the secondary school enrollment rates used by mrw. Second, the null hypothesis of an exogenous and identical level of technology in all countries is rejected. We also explain why the Solow model performed well despite the above shortcomings.     

A DEFENSE OF THE FOMC*

We defend the forecasting performance of the Federal Reserve Open Market Committee (FOMC) against the criticism of Christina and David Romer (2008, American Economic Review 98, 230–235) by assuming that the FOMC’s forecasts depict a worst‐case scenario that it uses to design decisions that are robust to misspecification of the staff’s model. We use a simple macro model and a plausible loss function to illustrate how such an interpretation of the FOMC’s forecasts can explain the findings of Romer and Romer, including the pattern of differences between FOMC forecasts and forecasts published by the staff of the Federal Reserve System in the Greenbook.     

Multiple steady states,indeterminacy, and cycles in a basic model of endogenous growth

The goal of this paper is to demonstrate that a basic model of endogenous growth with learning by doing may produce a rich array of outcomes. Starting point of our analysis is the Romer (1986a) approach. In contrast to Romer, however, we assume that one unit of investment shows different effects concerning the building up of physical and human capital, so that these variables cannot be merged into one single variable. With this assumption, it can be shown that multiple steady states, indeterminacy of equilibria, and persistent cycles may result in our model.     

Costly switching and investment volatility

Summary. This paper extends the literature on the optimal switching rule between two investments by considering the case where switching between investments is costly. The model builds on the classic framework of the multi-armed Bandit problem by explicitly incorporating two key assumptions. First, switching investments is costly. Second, only the investment operated by the investor evolves as a random walk. The objective of the investor is to maximize the discounted sum of expected net profits over the infinite horizon. The main result is that when the volatility of profits from investments increases, so does the minimum profit gain needed for an investor to switch investments.JEL Classification Numbers: C44, C61.I am indebted to Prajit K. Dutta for his guidance throughout this research. I am grateful for Presidents Summer 2000 Research Fellowship of Columbia University. I appreciate the comments from the anonymous referee. I also thank Lalith Munasinghe and Rajiv Sethi. I also thank Dr. Jong Myeon Kim for editing this version of the paper.     

Climate Change,Innovation, and Economic Growth: The Contributions of William Nordhaus and Paul Romer

ABSTRACT

William Nordhaus and Paul Romer shared the 2018 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for their work on long-run macroeconomic analysis. Nordhaus adapted the neoclassical growth model to study climate change, while Romer developed a model of innovation-based growth. The authors provide two distinct explanations of what drives growth, and employ contrasting methodologies for interpreting the results of their mathematical models. Macroeconomic policy in general, and climate policy in particular, would benefit from better integrating the theory and methods of these two laureates.     

On the herding instinct of interest rate forecasters

It is not uncommon to observe the published forecasts of economic commentators closely bunched together over long periods of time. In our case, the phenomenon is observed for eight national panels of economists who report monthly forecasts. A framework is developed that conveniently nests within it several simple, yet plausible forecasting rules, and allows us to explore the extent of the clustering phenomenon. First version received: June 1999/Final version received: February 2001     

中国基础设施投资的最优规模与最优次序——基于1996-2008年各省市地区面板数据分析

本文克服各项基础设施同时回归导致的多重共线性问题,基于基础设施的边际产出与最优规模分析框架,采用中国1996-2008年各省市地区面板数据实证研究发现:中国电力、燃气和水的生产与供应业、交通运输、仓储和邮电通信业、水利、环境和公共设施管理业等各项基础设施和政府总投资的边际产出分别为5.765、2.520、1.420和1.276;最优规模分别为4.66%、3.29%、5.02%和20.95%;各项基础设施的实际投资均低于最优规模。因此,为使政府投资收益最大化可按边际产出大小顺序优先次序投资;而根据各项基础设施投资的缺口和紧迫程度,则应按实际投资与最优规模差距由大到小顺序进行投资。     

Economic growth, skill-biased technical change and wage inequality: A model and estimations for the US and Europe

In recent literature skill-biased technical change has been viewed as a major cause for wage inequality. Some modelling and presentation of stylized facts have been undertaken for US time series data. A preliminary study of wage inequality in a model with knowledge as input in an aggregate production function has been presented by Riddell and Romer [General Purpose Technologies and Economic Growth, 1998, MIT Press]. Although some important forces determining wage inequality are widely accepted we know little about the quantitative impact of each source and differences across countries. We present a growth model of the Romer type with innovation-based technical change and two skill groups where the growth of knowledge, the relative supply of the two skill groups, externalities and substitution effects among the two groups are the driving forces for wage inequality. We undertake estimates for US time series data and contrast those estimates with results from some European countries. In particular, we compare parameter estimations for US and German time series data. The paper concludes that there is less wage inequality across skills in Europe in contrast to the US on the macroeconomic level. But, considering disaggregated data we observe some increases in inequality for Germany, too. Although our model reveals important variables for the explanation of wage inequality there may, however, also be other factors, such as trade unions, which have impacted the wage spread.