Simpson's paradox visualized: The example of the Rosiglitazone meta-analysis

<p>Abstract</p> <p>Background</p> <p>Simpson's paradox is sometimes referred to in the areas of epidemiology and clinical research. It can also be found in meta-analysis of randomized clinical trials. However, though readers are able to recalculate examples from hypothetical as well as real data, they may have problems to easily figure where it emerges from.</p> <p>Method</p> <p>First, two kinds of plots are proposed to illustrate the phenomenon graphically, a scatter plot and a line graph. Subsequently, these can be overlaid, resulting in a overlay plot. The plots are applied to the recent large meta-analysis of adverse effects of rosiglitazone on myocardial infarction and to an example from the literature. A large set of meta-analyses is screened for further examples.</p> <p>Results</p> <p>As noted earlier by others, occurrence of Simpson's paradox in the meta-analytic setting, if present, is associated with imbalance of treatment arm size. This is well illustrated by the proposed plots. The rosiglitazone meta-analysis shows an effect reversion if all trials are pooled. In a sample of 157 meta-analyses, nine showed an effect reversion after pooling, though non-significant in all cases.</p> <p>Conclusion</p> <p>The plots give insight on how the imbalance of trial arm size works as a confounder, thus producing Simpson's paradox. Readers can see why meta-analytic methods must be used and what is wrong with simple pooling.</p

Significance testing as perverse probabilistic reasoning

Truth claims in the medical literature rely heavily on statistical significance testing. Unfortunately, most physicians misunderstand the underlying probabilistic logic of significance tests and consequently often misinterpret their results. This near-universal misunderstanding is highlighted by means of a simple quiz which we administered to 246 physicians at two major academic hospitals, on which the proportion of incorrect responses exceeded 90%. A solid understanding of the fundamental concepts of probability theory is becoming essential to the rational interpretation of medical information. This essay provides a technically sound review of these concepts that is accessible to a medical audience. We also briefly review the debate in the cognitive sciences regarding physicians' aptitude for probabilistic inference

A multi-target compiler for CML-DEVS

International audienc

Customizing Websites Through Automatic Web Search

Part 7: Information VisualizationInternational audienceThe WorldWide Web has endured an incredible growth in the last decades. Nowadays, we can visit an unimaginable number of websites from different devices (laptops, mobiles, tablets...) in order to obtain immediate information. However, this information is separated in different resources and Web information search is unpleasant. The feeling of the users is frustrating when collecting information from different resources. Techniques such as Web personalization and Web customization have been an important research area during the last years. Web customization techniques have been widely used to develop website adaptation along the WorldWide Web. This customization is frequently performed by end-users that use the numerous tools available to carry out this assignment.This article presents Excore, a Web customization tool that permits end-users to customize their websites with automatic Web searches. The article presents the benefits introduced by Excore as a response to the drawbacks end-users experience while they perform their Web activities. Evaluation of the Web customization tool is also addressed in the paper. Evaluation is performed with stakeholders by means of tests and surveys. Results show that testers overcome the detected drawbacks with the use of Excore