Empirical testing of alternative price spread models in the South African maize market

Reduced-form price spread models have been recently utilized by Wohlgenant and Mullen, and Thompson and Lyon to evaluate the economic factors affecting the marketing margins for agricultural products. Drawing on Gardner, Heien, Buse and Brandow, Waugh, Tomek and Robinson, and others they specify alternative retail-farm price spread models and attempt to determine which best fit the data in the context of underlying theoretical rationale. This paper continues in the spirit of Wohlgenant and Mullen, and Thompson and Lyon by evaluating alternative specifications of the retail-farm price spread for white maize in South Africa. However, several important differences do remain. Wohlgenant and Mullen analyzed the price spread for beef using annual data, while Thompson and Lyon modeled the price spread for oranges using weekly data. The time period under consideration can be expected to affect the choice of model because fixed markup rules that might be evident using a short-run period of analysis (e.g., Thompson and Lyon) become untenable over the long run with underlying supply and demand shifts. In this paper, monthly data, which may be interpreted as an intermediate-run period, are used along with dichotomous supply-demand shifters. In addition, Brorsen et. al. have shown that price uncertainty affects the price spread in the marketing channels of agricultural commodities. Thus, the analysis in this paper extends the framework of Wohlgenant and Mullen, and Thompson and Lyon to include measures of price risk. Finally, like Brorsen et. al. this study pertains to the grain market, while Wohlgenant and Mullen, and Thompson and Lyon studied the marketing margin for non-storable commodities.     

应该将扩大消费需求提升到国家战略的高度

消费问题经过几十年的讨论,至今仍没有得到一些人的高度重视。重投资,重GDP的增长,不重视消费拉动的老毛病,一直制约着我国经济的可持续发展。事实上,如果我国消费水平再不上一个新台阶,还将制约我国经济的持续发展。应该将扩大消费需求提升到我国发展的战略高度来认识。一、应     

An empirical analysis of bank interest rate swaps

Considering the characteristics of banks that do and do not report interest rate swaps, the long-term interest rate exposure of a bank and the likelihood and extent of swap market participation are found to be positively related. Key to the finding is the inclusion of variables related to the provision of swap market intermediary services, which significantly explain both the likelihood of swap market participation and the notional value of outstanding swaps. The results suggest that the likelihood and extent of swap market participation by low-capitalized banks is less than for other banks.     

Single or double bounded contingent valuation? A Bayesian test

This paper evaluates the performance of asymptotic approximations of the Bayes factor to appraise the relative likelihoods of the bivariate and the restricted double bounded models for contingent valuation. The performance of the Bayes factor test is studied by Monte Carlo simulation showing that it correctly chooses the bivariate model when appropriate, but tends to over predict the double bounded model when the correlation coefficient is not estimated accurately. However, the quadratic error in estimating willingness to pay is reduced if the model preferred by the test is chosen. In addition, we consider the effect of averaging the estimates of WTP from both models, weighting each model with its posterior probability. The results show that ‘model averaging’ across the competing hypothesis further reduces the squared error. The applications with two data sets on National Parks show that the test rejects the restricted double bounded hypotheses against the bivariate model.     

Business Ethics: The Bottom Line

Teaching Business Ethics -     

Sustaining Collusion in Growing Markets

The impact of demand growth on the collusion possibilities is investigated in a Cournot supergame where market growth may trigger future entry and the collusive agreement is enforced by the most profitable ‘grim trigger strategies’ available. It is shown that even in situations where perfect collusion can be sustained after entry, coping with a potential entrant in a market which is growing over time may completely undermine any pre‐entry collusive plans of the incumbent firms. This is because, before entry, a deviation and the following punishment phase may become more attractive thanks to their additional effect in terms of delaying entry.     

Bayesian MCMC Mapping of Quantitative Trait Loci in a Half-sib Design: a Graphical Model Perspective

Graphical models provide a powerful and flexible approach to the analysis of complex problems in genetics. While task-specific software may be extremely efficient for any particular analysis, it is often difficult to adapt to new computational challenges. By viewing these genetic applications in a more general framework, many problems can be handled by essentially the same software. This is advantageous in an area where fast methodological development is essential. Once a method has been fully developed and tested, problem-specific software may then be required. The aim of this paper is to illustrate the potential use of a graphical model approach to genetic analyses by taking a very simple and well-understood problem by way of example.     

IntraLATA long-distance demand: carrier choice, usage demand and price elasticities

Competition in the long-distance market in the US continues to intensify; the 1996 Telecommunications Act has led to increased competition in long-distance telephony especially as the Regional Bell Operating Companies have begun to gain entry to long-haul, long-distance markets. In order to better understand the implications of having increased service offerings, models of how customers choose between carriers (and the impact of this choice on subsequent usage) will be useful. We develop the first publicly available models that simultaneously estimate choice and usage for intraLATA long-distance in the US. Utilizing a generalized Tobit model, the price responsiveness of usage and carrier choice are estimated. The results are generally consistent with expectations both in terms of theory and of practical experience in the industry.