Should causal models always be Markovian? The case of multi-causal forks in medicine

The development of causal modelling since the 1950s has been accompanied by a number of controversies, the most striking of which concerns the Markov condition. Reichenbach's conjunctive forks did satisfy the Markov condition, while Salmon's interactive forks did not. Subsequently some experts in the field have argued that adequate causal models should always satisfy the Markov condition, while others have claimed that non-Markovian causal models are needed in some cases. This paper argues for the second position by considering the multi-causal forks, which are widespread in contemporary medicine (Section 2). A non-Markovian causal model for such forks is introduced and shown to be mathematically tractable (Sections 6, 7, and 8). The paper also gives a general discussion of the controversy about the Markov condition (Section 1), and of the related controversy about probabilistic causality (Sections 3, 4, and 5

Chromosome 14 linkage analysis and mutation study of 2 serpin genes in allergic asthmatic families

BACKGROUND Genome and chromosome screens reported DNA markers on chromosome 14 linked to allergic asthma or intermediate phenotypes in several populations. OBJECTIVE We sought to perform a linkage study on chromosome 14 and a further association study on candidate genes mapped in the region found to be linked to allergic asthma or intermediate phenotypes. METHODS The study consisted of a sample of 189 families (847 genotyped individuals) from a restricted geographic area in northeastern Italy. The subjects were characterized for the following phenotypes: allergic asthma, total serum IgE levels, skin prick test responses, and bronchial hyperresponsiveness (BHR) to methacholine. Genotyping was done with 14 DNA markers and 4 polymorphisms in the genes encoding alpha(1)-anti-trypsin and alpha(1)-antichymotrypsin (ACT). RESULTS Multipoint analysis indicated a potential linkage of BHR with marker D14S617 (nonparametric linkage z score = 2.32, P =.01). Transmission disequilibrium of Thr -15Ala in the gene encoding ACT was observed with all the phenotypes investigated: allergic asthma, BHR, total IgE levels, or skin prick test responses (P =.041,.02,.0053, or.026, respectively). CONCLUSION Chromosome 14 screening and transmission disequilibrium testing on the gene encoding ACT suggest that it or a closely located gene may be involved in susceptibility to allergic asthma in the Italian population

Challenges to Bayesian Confirmation Theory

While Bayesian analysis has enjoyed notable success with many particular problems of inductive inference, it is not the one true and universal logic of induction. I review why the Bayesian approach fails to provide this universal logic of induction. Some of the reasons arise at the global level through the existence of competing systems of inductive logic. Others emerge through an examination of the individual assumptions that, when combined, form the Bayesian system: that there is a real valued magnitude that expresses evidential support, that it is additive and that its treatment of logical conjunction is such that Bayes' theorem ensues