I participated with pleasure in discussions on 30 September 2011 in Warsaw during the ‘Diff erences in Health in the Polish population’ Conference, which aimed at critical assessment of fi rst baseline results from the PONS study, a pilot prospective cohort established in Poland. Th e PONS study results from the ‘Closing the Health Gap’ Report recommending an attempt to start building in Centra...

In this paper we propose a measure of sim­ ilarity /association between two partitions of a set of objects. Our motivation is the desire to use the measure to characterize the quality or accuracy of clustering algorithms by some­ how comparing the clusters they produce with "ground truth" consisting of classes as­ signed by manual means or some other means in whose veracity there is confidence....

The external validity of causal findings is a focus long-standing debates in the social sciences. Although issue has been extensively studied at conceptual level, practice few empirical studies include an explicit analysis that directed toward externally valid inferences. In this article, we make three contributions to improve approaches for validity. First, propose formal framework encompasses...