Testing for Zipf’s law: A common pitfall

It is noted that the regression procedure commonly used when testing for Zipf’s law is erroneous.     

The Oaxaca decomposition generalized to a continuous group variable

Almost universally, the Oaxaca (1973) decomposition is used to compare the outcomes between two discrete groups, e.g., black and white. In many applications, however, groups are not readily divided into discrete bins. The purpose of this paper is to extend the Oaxaca decomposition to examine differences amongst groups that are most naturally modeled as at points in a continuum. The gap can vary by values of the group variable.     

Bootstrapping structural VARs: Avoiding a potential bias in confidence intervals for impulse response functions

Constructing bootstrap confidence intervals for impulse response functions (IRFs) from structural vector autoregression (SVAR) models has become standard practice in empirical macroeconomic research. The accuracy of such confidence intervals can deteriorate severely, however, if the bootstrap IRFs are biased. We document an apparently common source of bias in the estimation of the VAR error covariance matrix which can be easily reduced by a scale adjustment. This bias is generally unrecognized because it only affects the bootstrap estimates of the error variance, not the original OLS estimates. Nevertheless, as we illustrate here, analytically, with sampling experiments, and in an example from the literature, the bootstrap error variance bias can have significant distorting effects on bootstrap IRF confidence intervals. We also show that scale-adjusted bootstrap confidence intervals can be expected to exhibit improved coverage accuracy.     

A comparison of proxy variable and stochastic latent variable approaches to the measurement of bias in technological change in south african agriculture*

Technical change is inherently unobservable and has conventionally been represented by proxy variables, from simple time trends to more sophisticated knowledge stock variables. This paper follows Lambert and Shonkwiler (1995) in modelling technical change as a stochastic unobservable variable and tests this formulation against the alternative of using R&D and patent indices. This is done by fitting a system of share equations, derived from the dual profit function, to production data for South African agriculture. Each equation includes both unobserved technical change components and technical proxy variables. Variable deletion tests show that conventional proxy variables fail to explain the biases of technological change, while cointegration tests show that technical change is both stochastic and biased. The latent variables provide estimates of biases that are consistent with past studies and the historical record and can be explained by policy change in South Africa following WWII. The demonstration of high rates of return to R&D is not sufficient to justify R&D activity when biased technological change exacerbates input use and welfare distortions within and without the sector. * We thank the University of Pretoria for funding the study and the referees and delegates for many useful comments.     

Overconfidence as a social bias: Experimental evidence

The overconfidence bias is discussed extensively in economic studies, yet fails to hold experimentally once monetary incentives and feedback are implemented. We consider overconfidence as a social bias. For a simple real effort task, we show that, individually, economic conditions effectively prevent overconfidence. By contrast, the introduction of a very basic, purely observational social setting fosters overconfident self-assessments. Additionally, observing others’ actions effectively eliminates underconfidence compared to the individual setting.     

Evolution in games with a continuous action space

Allowing for games with a continuous action space, we investigate how evolutionary stability, the existence of a uniform invasion barrier, local superiority and asymptotic stability relate to each other. This is done without restricting the populations of which we want to investigate the stability to monomorphic population states or to strategies with finite support. The authors have benefitted from careful and precise comments by Gerard van der Laan, Jan van Mill, the editor and an anonymous referee. Matthijs van Veelen gratefully acknowledges financial support by the Netherlands’ Organization for Scientific Research (NWO).     

The reciprocity theorem in a model with variable factor supply

The reciprocity theorem is extended to include variable factor supply in a specific factor model.     

公益部门：蕴藏巨大就业潜力的部门——关于扩大我国就业途径的一些思考与建议

公益部门已是发达国家扩大就业的重要领域。结合发达国家的经验，文章指出随着我国市场化改革和政府职能转变，公益部门的发展将为扩大就业提供新途径，并为此提出相关政策建议。     

Errors in variables in panel data with a binary dependent variable

In a conditional logistic regression model for panel data when independent variables are subject to measurement error, the usual estimator, obtained by a regression on the observed independent variables, is asymptotically biased. We introduce a bias-adjusted estimator, which is examined asymptotically under conditions that are appropriate when the measurement error is small but non-negligible.     

Multiplicative uncertainty in a model without inflationary bias

This paper shows that an increase in the degree of multiplicative uncertainty regarding the effectiveness of monetary policy will reduce social loss when policymaker’s preferences are highly uncertain. This result is still valid even when there is no distortion in the market.     

Dealing with small sample bias in post-crisis samples

In this paper, we demonstrate that using finite sample correction bootstrapping techniques is advisable in samples that cover less than two complete business cycles, even when high-frequency data seemingly provide a sufficient number of observations to overcome the small sample bias. This is particularly relevant in the current research environment. Because the recent financial crisis is considered as a structural break, research on current problems is often conducted using post-crisis data. That is, the available samples cover only a few years of data, often spanning only one business cycle or even less. We provide ample simulation-based evidence that samples of daily or monthly dynamic data covering periods of this magnitude are prone to a fairly substantial bias. Moreover, we are able to show that standard bootstrap-based bias correction techniques still work in those cases.     

Linkages in international stock markets: evidence from a classification procedure

In this article, we propose a new approach to evaluate the predictable components in stock indices using a boosting-based classification technique, and we use this method to examine causality among the three main stock market indices in the world during periods of large positive and negative price changes. The empirical evidence seems to indicate that the Standard & Poors 500 index contains incremental information that is not present in either the FTSE 100 index (Financial Times Stock Exchange Index) or the Nikkei 225 index, and that could be used to enhance the predictability of the large positive and negative returns in the three main stock market indices in the world. This in turn would suggest a causality relationship running from the Standard & Poors 500 index to both the FTSE 100 and the Nikkei 225 indices.     

Existence of a continuous utility function with path monotonicity: the Wold approach

Summary This paper uses the approach of Wold to prove the existence of a continuous utility function on a subset ofR ⁿ with a path monotonicity assumption. This result is then extended to a Banach space.The research for this paper was begun while visiting the University of Cambridge and the London School of Economics in 1988. I should like to thank Dr. A. Beardon, Professor M. Desai, Professor L. Foldes and Dr. A. Horsley for their hospitality. Also, I am grateful to an anonymous referee for comments that led to an improvement in the exposition.     

Estimating a continuous time portfolio selection model: An application with UK data

An empirical assessment of a continuous time portfolio selection model is studied for the UK economy between 1970 and 1996. The estimates obtained from this study are both statistically significant and consistent with the model's predictions. The estimate of risk aversion parameter refers to low risk aversion which is consistent with the optimal risky asset holding parameter. Furthermore, the estimated parameters of the asset pricing relationship are also found to be consistent with the historical values of the stock prices. First version received: February 1998/final version received: March 1999     

Auctions with variable supply: Uniform price versus discriminatory

We examine an auction in which the seller determines the supply after observing the bids. We compare the uniform price and the discriminatory auction in a setting of supply uncertainty, where uncertainty is caused by the interplay of two factors: the seller's private information about marginal cost and the seller's incentive to sell the profit-maximizing quantity, given the received bids. In every symmetric mixed strategy equilibrium, bidders submit higher bids in the uniform price auction than in the discriminatory auction. In the two-bidder case, this result extends to the set of rationalizable strategies. As a consequence, we find that the uniform price auction generates a higher expected revenue for the seller and a higher trade volume.     

An example of multiple minima in a Cochrane-Orcutt procedure with multiple autocorrelation

We provide an example, based on an equation of the Canadian-US exchange rate, of multiple minima in a generalized Cochrane-Orcutt procedure. Our experiments suggest the need for search procedures in order to correctly identify autocorrelation structures.     

Time as a strategic variable: business hours in the gasoline market

A popular argument in policy discussions on the liberalization of business hours proceeds on the assumption that business hours are strategic complements: if some firms open longer hours, competitors will be forced to extend their opening hours too. We provide first empirical evidence on the impact of competition and the form of strategic interaction in business hours between firms by using detailed information on business hours as well as the location of retail gasoline stations in Austria. Our findings reject the presumption of business hours being strategic complements. Firms tend to have longer opening hours in a more competitive environment.