Teacher sorting, teacher quality, and student composition

Using panel data for Norwegian schools, we establish a two-equation supply and demand model for teachers with approved education. Taking into account nationally determined teacher pay and a strict teacher appointment rule, the data enable us to separately estimate supply and demand functions for certified teachers. The results clearly indicate that the student body composition, and in particular students belonging to ethnic minorities, influences both teacher supply and teacher demand. The implied negative relationship between excess demand for certified teachers and the share of minority students is likely to be important for teacher quality.     

The Incremental Predictive Information Associated with Using Theoretical New Keynesian DSGE Models vs. Simple Linear Econometric Models*

In this paper we construct output gap and inflation predictions using a variety of dynamic stochastic general equilibrium (DSGE) sticky price models. Predictive density accuracy tests related to the test discussed in Corradi and Swanson [Journal of Econometrics (2005a), forthcoming] as well as predictive accuracy tests due to Diebold and Mariano [Journal of Business and Economic Statistics (1995) , Vol. 13, pp. 253–263]; and West [Econometrica (1996) , Vol. 64, pp. 1067–1084] are used to compare the alternative models. A number of simple time‐series prediction models (such as autoregressive and vector autoregressive (VAR) models) are additionally used as strawman models. Given that DSGE model restrictions are routinely nested within VAR models, the addition of our strawman models allows us to indirectly assess the usefulness of imposing theoretical restrictions implied by DSGE models on unrestricted econometric models. With respect to predictive density evaluation, our results suggest that the standard sticky price model discussed in Calvo [Journal of Monetary Economics (1983), Vol. XII, pp. 383–398] is not outperformed by the same model augmented either with information or indexation, when used to predict the output gap. On the other hand, there are clear gains to using the more recent models when predicting inflation. Results based on mean square forecast error analysis are less clear‐cut, although the standard sticky price model fares best at our longest forecast horizon of 3 years, it performs relatively poorly at shorter horizons. When the strawman time‐series models are added to the picture, we find that the DSGE models still fare very well, often outperforming our forecast competitions, suggesting that theoretical macroeconomic restrictions yield useful additional information for forming macroeconomic forecasts.     

The Analysis of Welfare Effects of an Environmental Product Tax: An Application to the Taxation of Car Tyres in Hungary

A sophisticated welfare analysis developed by Morris and Kis (1996) is presented here for the study of the effect of a product charge tax on the car tyre market in Hungary. The analysis is extended and complemented in this paper by, first, using the AIDS model and an algorithm developed by Galarraga and Markandya (2000) to estimate demand elasticities from limited data and, second, including the income effects into the analysis. The latter does not have much impact on the results but the generalisation of the model might be useful for the analysis of different goods where the proportion of income spent on them is more important.     

Inverse of the Berge maximum theorem

Summary We consider an inverse of the Berge maximum theorem. We also give an application of our result to fixed point theory.     

Product and country substitution in imports: An empirical comparison of theoretical concepts

Product and Country Substitution in Imports: An Empirical Comparison of Theoretical Concepts. — The paper focuses on the shortcomings of current unit-values based measures for estimating product and country substitution in imports. The results of the bilateral index number technique in measuring changes in the country composition or product mix of imports were found to be inadequate, which was shown in an analysis of data on the French import market for chairs. An improved technique is briefly summarized, and its applicability compared with the bilateral index number technique. The new method performed accurately and provided a reliable basis for a refined analysis of changes within import markets.     

220KV线路微机保护器的运行与维护

随着220KV微机线路保护的广泛应用,微机线路保护的一些缺陷也开始逐渐显现出来。本文针对微机线路经常出现的一些故障和缺陷,提出了在220kv微机保护运行管理中要注意的一些问题。     

An extremely simple proof of the K-K-M-S Theorem

Summary.  An extremely simple proof of the K-K-M-S Theorem is given involving only Brouwer’s fixed point theorem and some elementary calculus. A function is explicitly given such that a fixed point of it yields an intersection point of a balanced collection of sets together with balancing weights. Moreover, any intersection point of a balanced collection of sets together with balancing weights corresponds to a fixed point of the function. Furthermore, the proof can be used to show -balanced versions of the K-K-M-S Theorem, with -balancedness as introduced in Billera (1970). The proof makes clear that the conditions made with respect to by Billera can be even weakened. Received: January 22, 1996; revised version June 9, 1996     

Non-addictive habits: optimal consumption-portfolio policies

We formulate a model of preferences with non-addictive habits, where consumption is required to be non-negative at all times, but can fall below a “standard of living” index that aggregates past consumption. We study the consumption-portfolio problem taking account of the non-negativity constraint on consumption, and provide a constructive proof for the existence of an optimal policy on a finite time-horizon [0,T]. We show that the consumption constraint binds up to an endogenous stopping time τ∗∈[0,T], after which it remains slack until T. A decomposition of constrained consumption involving an Asian average-strike capped call-option is demonstrated.     

Exit problems in regime-switching models

This paper provides a general framework for pricing of perpetual American and real options in regime-switching Lévy models. In each state of the Markov chain, which determines switches from one Lévy process to another, the payoff stream is a monotone function of the Lévy process labeled by the state. This allows for additional switching within each state of the Markov chain (payoffs can be different in different regions of the real line). The pricing procedure is efficient even if the number of states is large provided the transition rates are not very large w.r.t. the riskless rates. The payoffs and riskless rates may depend on a state. Special cases are stochastic volatility models and models with stochastic interest rate; both must be modeled as finite-state Markov chains. As an application, we solve exit problems for a price-taking firm, and study the dependence of the exit threshold on the interest rate uncertainty.     

A Simple Test for Cointegration in Dependent Panels with Structural Breaks*

This paper develops a very simple test for the null hypothesis of no cointegration in panel data. The test is general enough to allow for heteroskedastic and serially correlated errors, unit‐specific time trends, cross‐sectional dependence and unknown structural breaks in both the intercept and slope of the cointegrated regression, which may be located at different dates for different units. The limiting distribution of the test is derived, and is found to be normal and free of nuisance parameters under the null. A small simulation study is also conducted to investigate the small‐sample properties of the test. In our empirical application, we provide new evidence concerning the purchasing power parity hypothesis.