Classification de variables et analyse multivariée de données mixtes issues d’une étude BCI

International audienceL'objectif de ce travail est de traiter des données complexes issues de la technique des Brain Computer Interfaces (BCI) au moyen de méthodes statistiques multivariées (approche PCAmix et classification de variables) afin de mieux comprendre et interpréter les relations qui existent entre elles. Cet article présente ainsi la classification de variables qui a pour but de réunir des variables fortement liées entre elles. L'approche proposée fonctionne avec des données mixtes, c'est à dire des données contenant des variables numériques et des variables catégorielles. Deux algorithmes de classification de variables sont décrits : un de classification hiérarchique et un autre de partitionnement de type k-means. Une rapide description de la méthode PCAmix (qui permet de faire de l'analyse en composantes principales pour des données mixtes) est fournie, vu que le calcul des variables synthétiques résumant les classes de variables obtenues est fondé sur cette méthode multivariée. Enfin, les approches PCAmix et ClustOfVar (implémentées dans les packages R ClustOfVar et PCAmixdata) sont mises en oeuvre sur les données réelles issues de l'étude BCI. Des recommandations, reposant non seulement sur des critères de performances, d'efficience mais aussi de satisfaction, ont pu être faites concernant le choix d'interface dans l'usage des claviers virtuels, notamment pour des personnes avec des problèmes moteurs tels que la maladie de Charcot. ABSTRACT. The aim of this work is to analyze complex data from a Brain Computer Interfaces (BCI) study using multivariate statistical methods (PCAmix approach and clustering of variables) to better understand and interpret their relationships. This article presents clustering of variables which aim is to lump together strongly related variables. The proposed approach works on a mixed data set, i.e. on a data set which contains numerical variables and categorical variables. Two algorithms of clustering of variables are described : a hierarchical clustering and a k-means type clustering. A brief description of PCAmix method (that is a principal component analysis for mixed data) is provided, since the calculus of the synthetic variables summarizing the obtained clusters of variables is based on this multivariate method. Finally, the PCAmix and ClustOfVar approaches (implemented in the R packages ClustOfVar and PCAmixdata) are illustrated on a real dataset from a BCI (brain computer interface) study. Recommendations, based not only on performance, efficiency, but also on satisfaction criteria, could be made concerning the choice of interface in the use of virtual keyboards, especially for people with motor disorder such as Charcot's disease. MOTS-CLÉS. Classification de variables, données mixtes, analyse en composantes principales, packages R, brain computer interface, analyse multivariée des données, visualisation des données. KEYWORDS. clustering of variables, mixed data, principal component analysis for mixed data, R packages, brain computer interface, multivariate data analysis, data visualization

Are categorical deniers different? Understanding demographic, personality, and psychological differences between denying and admitting sex offenders

The purpose of this study was to establish whether there were demographic, personality, or psychological differences between a sample of 40 incarcerated sex offenders in categorical denial and 37 sex offenders admitting responsibility in an Australian minimum-security unit. Categorical deniers had lower IQs, were older, and were more likely to be child molesters. Criminogenically, there were no differences between categorical deniers and those who admitted their offences in relation to Static-99 risk scores. Psychologically, offenders denying their offences were significantly more shame-prone, and likely to use externalization as a method of impression-management. They were also more compulsive than those admitting their offences, but less antisocial and sadistic, when compared on personality indices. The study is limited by the small sample size however implications for further research and the treatment of categorical deniers are discussed

Evidence-based effect size estimation:An illustration using the case of acupuncture for cancer-related fatigue

<p>Abstract</p> <p>Background</p> <p>Estimating a realistic effect size is an important issue in the planning of clinical studies of complementary and alternative medicine therapies. When a minimally important difference is not available, researchers may estimate effect size using the published literature. This evidence-based effect size estimation may be used to produce a range of empirically-informed effect size and consequent sample size estimates. We provide an illustration of deriving plausible effect size ranges for a study of acupuncture in the relief of post-chemotherapy fatigue in breast cancer patients.</p> <p>Methods</p> <p>A PubMed search identified three uncontrolled studies reporting the effect of acupuncture in relieving fatigue. A separate search identified five randomized controlled trials (RCTs) with a wait-list control of breast cancer patients receiving standard care that reported data on fatigue. We use these published data to produce best, average, and worst-case effect size estimates and related sample size estimates for a trial of acupuncture in the relief of cancer-related fatigue relative to a wait-list control receiving standard care.</p> <p>Results</p> <p>Use of evidence-based effect size estimation to calculate sample size requirements for a study of acupuncture in relieving fatigue in breast cancer survivors relative to a wait-list control receiving standard care suggests that an adequately-powered phase III randomized controlled trial comprised of two arms would require at least 101 subjects (52 per arm) if a strong effect is assumed for acupuncture and 235 (118 per arm) if a moderate effect is assumed.</p> <p>Conclusion</p> <p>Evidence-based effect size estimation helps justify assumptions in light of empirical evidence and can lead to more realistic sample size calculations, an outcome that would be of great benefit for the field of complementary and alternative medicine.</p

Proceedings of the Third Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

The proceedings of the 3rd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, imaging, and computational work on DBS for the treatment of neurological and neuropsychiatric disease. Significant innovations of the past year are emphasized. The Think Tank\u27s contributors represent a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers, and members of industry. Presentations and discussions covered a broad range of topics, including policy and advocacy considerations for the future of DBS, connectomic approaches to DBS targeting, developments in electrophysiology and related strides toward responsive DBS systems, and recent developments in sensor and device technologies

2020 taxonomic update for phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV