Modelling soccer matches using bivariate discrete distributions with general dependence structure

In this paper copulas are used to generate bivariate discrete distributions. These distributions are fitted to soccer data from the English Premier League. An interesting aspect of these data is that the primary variable of interest, the discrete pair shots-for and shots-against, exhibits negative dependence; thus, in particular, we apply bivariate Poisson-related distributions that allow such dependence. The paper focuses on Archimedian copulas, for which the dependence structure is fully determined by a one-dimensional projection that is invariant under marginal transformations. Diagnostic plots for copula fit based on this projection are adapted to deal with discrete variables. Covariates relating to within-match contributions such as numbers of passes and tackles are introduced to explain variability in shot outcomes. The results of this analysis would appear to support the notion that playing the 'beautiful game' is an effective strategy—more passes and crosses contribute to more effective play and more shots on the goal.     

Two new proofs of Afriat’s theorem

Summary. We provide two new, simple proofs of Afriats celebrated theorem stating that a finite set of price-quantity observations is consistent with utility maximization if, and only if, the observations satisfy a variation of the Strong Axiom of Revealed Preference known as the Generalized Axiom of Revealed PreferenceReceived: 12 June 2003, Revised: 9 October 2003, JEL Classification Numbers: D11, C60.Correspondence to: A. Fostel     

Modelling quality in replacement and inspection maintenance

Heterogeneity in component and maintenance quality is considered in the context of age-based inspection and replacement for a single component system. A three-state component failure model is assumed, with a defective state preceding the failed state. Heterogeneity in maintenance intervention is modelled by supposing that inspections may induce the defective state. Component heterogeneity is modelled by supposing that the population of components comprises a mixture of the weak and strong, and that the mixing proportion and cost of components vary between suppliers. Within this framework, the impact, on system reliability and cost, of switching component or maintenance supplier is determined. Broadly, our finding is that one is much more inclined to switch supplier in order to obtain higher quality maintenance than to obtain higher quality components. A gas pressure control valve is used to illustrate our ideas.     

On cores and indivisibility

An economic model of trading in commodities that are inherently indivisible, like houses, is investigated from a game-theoretic point of view. The concepts of balanced game and core are developed, and a general theorem of Scarf's is applied to prove that the market in question has a nonempty core, that is, at least one outcome that no subset of traders can improve upon. A number of examples are discussed, and the final section reviews a series of other models involving indivisible commodities, with references to the literature.