Benchmark priors for Bayesian model averaging

In contrast to a posterior analysis given a particular sampling model, posterior model probabilities in the context of model uncertainty are typically rather sensitive to the specification of the prior. In particular, ‘diffuse’ priors on model-specific parameters can lead to quite unexpected consequences. Here we focus on the practically relevant situation where we need to entertain a (large) number of sampling models and we have (or wish to use) little or no subjective prior information. We aim at providing an ‘automatic’ or ‘benchmark’ prior structure that can be used in such cases. We focus on the normal linear regression model with uncertainty in the choice of regressors. We propose a partly non-informative prior structure related to a natural conjugate g-prior specification, where the amount of subjective information requested from the user is limited to the choice of a single scalar hyperparameter g_0j. The consequences of different choices for g_0j are examined. We investigate theoretical properties, such as consistency of the implied Bayesian procedure. Links with classical information criteria are provided. More importantly, we examine the finite sample implications of several choices of g_0j in a simulation study. The use of the MC³ algorithm of Madigan and York (Int. Stat. Rev. 63 (1995) 215), combined with efficient coding in Fortran, makes it feasible to conduct large simulations. In addition to posterior criteria, we shall also compare the predictive performance of different priors. A classic example concerning the economics of crime will also be provided and contrasted with results in the literature. The main findings of the paper will lead us to propose a ‘benchmark’ prior specification in a linear regression context with model uncertainty.     

An integrative analysis of business bankruptcy in Australia

This paper proposes an integrative and dynamic approach for analyzing business failure. The simultaneous estimation results obtained with Australian data indicate significant associations between bankruptcy rates in different industries. Most of these associations are positive and hence implying that bankruptcy in one industry can inflict a ‘domino’ effect on other industries. The estimated significant negative association between current and lagged bankruptcy rates in the industries under consideration lend support to the survival of the fittest hypothesis. The estimation results also highlight the important effects of industry, domestic and international economic conditions on bankruptcy rates.     

Valuing the implicit guarantee of the Federal National Mortgage Association

The paper analyzes the guarantee of the Federal National Mortgage Association (FNMA). Rather than try to price the guarantee, we used time-series estimates of its value from Kane and Foster to infer the behavior of FNMA in exploiting the guarantee. The results are consistent with a model that predicts that FNMA does not take as much risk as it might. Rather, it trades off risk and return, but it does increase risk and exploit the guarantee when it gets in trouble (as it did in 1981).We have received helpful research assistance from Peter Carr and Bruno Gerard.     

Decision-making under uncertainty – A field study of cumulative prospect theory

The presented research tests cumulative prospect theory (CPT, [Kahneman, D., Tversky, A., 1979. Prospect theory: An analysis of decision under risk. Econometrica 47, 263–291; Tversky, A., Kahneman, D., 1981. The framing of decisions and the psychology of choice. Science 211, 453–480]) in the financial market, using US stock option data. Option prices possess information about actual investors’ preferences in such a way that an exploitation of conventional option analysis, along with theoretical relationships, makes it possible to elicit investor preferences. The option data in this study serve for estimating the two essential elements of the CPT, namely, the value function and the probability weighting function. The main part of the work focuses on the functions’ simultaneous estimation under CPT original parametric specification. The shape of the estimated functions is found to be in line with theory. Comparing to results of laboratory experiments, the estimated functions are closer to linearity and loss aversion is less pronounced.     

Determinants of GNMA Mortgage Prices

This paper contrasts three different arbitrage-based models for the pricing of GNMA securities, and analyzes the effect of different assumptions about the call policy pursued by the issuers of the underlying mortgages. Both the nature of the interest-rate uncertainty captured by the model and the assumed call policy have a major effect on the yield differentials predicted between GNMA securities and Treasury Bonds.     

Larry Moss and the Struggle Against Racism by the Whately Professors of Political Economy

In this note, we highlight an important consideration of Larry Moss's life's work, the continual struggle within economics against racism. Larry initiated and supported the symposium on eugenics published by the American Journal of Economics and Sociology in July 2005. He edited the volume Social Inequality, Analytical Egalitarianism and the March Toward Eugenic Explanations in the Social Sciences in August 2008. These constitute obvious signs of Larry's concern.
He conjectured that the Trinity College Dublin political economists who held the Whately professorship should be thought of as a school. Such a school was in fact identified in 1850 by an outsider who pointed to their shared opposition to racial explanations within an institutional setting. That shared opposition allowed them to speak against the narrow interests of the rulers of the country. Of course, other political economists of the time, Mill in particular, were also emphatic in their anti-racism. Thus, not only do we need to take up Larry's challenge to describe the Trinity College school but we must also seek its connections with the Scottish-English group of anti-racists.     

Return and risk in initial public offerings of both shares and warrants

In the past few years there has been an increasing number of new issues of shares of common stock together with warrants intended to raise interest in initial public offerings of relatively young, growing firms. In this study we examine the pricing efficiency of stocks and warrants offered simultaneously to the public as a single unit. We present a model for evaluating the warrants in such offerings and test it empirically against data from the Tel-Aviv Stock Exchange, where such offerings have become standard. We find that the issued units are usually undervalued, allowing for significant abnormal positive returns. But, while the warrants are usually underpriced, the stocks are overpriced. Largely consistent with the evidence from other financial markets around the world, we also find abnormal negative rates of return in the long run.     

Obstacles to Developing Indigenous Small and Medium Enterprises: An Empirical Assessment

The article reports the results of field surveys conducted inSri Lanka's leather industry and Tanzania's furniture industry.It outlines an approach to learning how small and medium enterprises(SMES) perceive the impact of financial, regulatory, technical,marketing, and other input constraints, and to evaluating theresults in relation to other empirical indicators. Lack of accessto finance emerges as the binding constraint for smaller, lessestablished firms in Sri Lanka and for all of Tanzania's SMES—notonly is informal financing limited for Tanzania's firms, evenfirms of adequate size and experience have difficulty borrowingfrom banks, and, if they do borrow, have difficult relationswith their lenders. In Tanzania, regulatory and tax constraintsappear largest for the smallest firms, declining somewhat asfirms grow: because enforcement is comprehensive, the bureaucraticburden of negotiating with government officials is greatestfor small firms. By contrast, in Sri Lanka the regulatory burdenrises with firm size, because enforcement is more stringentfor the larger and more visible firms. Constraints on physicalinputs continue to inhibit Sri Lankan SMES—a legacy ofexcessive vertical integration by parastatals. Technical constraintsare appraised as most significant by relatively educated entrepreneurswith some involvement in high-quality market niches.     

Transfers in Spanish State Retirement Pensions

A central issue in the recent reforms of state pensions in Spain has been to increase the proportionality between contributions and benefits along actuarially fair lines. The aim of this paper is to quantify the transfer component of social security retirement pensions, with transfer being understood as the difference between the pension effectively received and that which would be received under a system of actuarial fairness. The analysis is placed within a life-cycle framework, with particular reference to the distributive effects by income level. The results show that, in the past, there was a marked bias in favour of the objective of intergenerational and intragenerational redistribution, to the detriment of the objective of income insurance. This paper examines the factors that determine the final value of the transfer component within the entire Spanish pensions system.     

Basel’s value-at-risk capital requirement regulation: An efficiency analysis

We analyze the optimal portfolio policies of expected utility maximizing agents under VaR Capital Requirement (VaR-CR) regulation in comparison to the optimal policy under exogenously-imposed VaR Limit (VaR-L) and Limited-Expected-Loss (LEL) regulations. With VaR-CR regulation the agent strategy consists of simultaneous decisions on both the portfolio VaR and on the implied amount of required eligible capital. As a result, the performance of VaR-CR regulation depends on its design (the parameter n) and the agent preferences. We show that an optimal VaR-CR regulation allows the regulator on the one hand, to completely eliminate the exposure to the largest losses, which may jeopardize the existence of the institution, and on the other hand, to restrain the portfolio exposure to all other losses. These results rationalize the current Basel regulations. However, the analysis shows also that there is an optimal level of required eligible capital from the regulator standpoint. Counter-intuitively, any requirement above this optimal level is inefficient as it leads to a smaller amount of actually maintained eligible capital and thereby to a larger exposure to the most adverse states of the world. Unfortunately, the current Basel’s range of required levels (n = 3–4) is within this inefficient range. Moreover, with an inefficient regulation the agent might employ an inefficient reporting and disclosure procedure.