Fitting multiplicative models by robust alternating regressions.

In this paper a robust approach for fitting multiplicative models is presented. Focus is on the factor analysis model, where we will estimate factor loadings and scores by a robust alternating regression algorithm. The approach is highly robust, and also works well when there are more variables than observations. The technique yields a robust biplot, depicting the interaction structure between individuals and variables. This biplot is not predetermined by outliers, which can be retrieved from the residual plot. Also provided is an accompanying robust R-2-plot to determine the appropriate number of factors. The approach is illustrated by real and artificial examples and compared with factor analysis based on robust covariance matrix estimators. The same estimation technique can fit models with both additive and multiplicative effects (FANOVA models) to two-way tables, thereby extending the median polish technique.Alternating regression; Approximation; Biplot; Covariance; Dispersion matrices; Effects; Estimator; Exploratory data analysis; Factor analysis; Factors; FANOVA; Least-squares; Matrix; Median polish; Model; Models; Outliers; Principal components; Robustness; Structure; Two-way table; Variables; Yield;

Rapid decline in child mortality in a rural area of Senegal

Retrospective and prospective demographic and health data collected on the population of Mlomp (6352 people in 1985), a rural area of Senegal, show that the probability of dying before the age of 5 years declined from 350 to 81 deaths per hundred livebirths in the last 25 years. This dedine is greater and faster than ever observed in Senegal. The drop in mortality mainly results from improved access to new and efficient health services-a dispensary and a maternity clinic-and from growth surveillance, health education, vaccination and malaria programmes initiated in the 1960s and 1970s. Although socioeconomic conditions have changed in the area, the influence of classical factors such as women's educational level and improvement in transportation has probably been limited. Deaths from diseases that can be prevented by immunization (such as neonatal tetanus, measles, whooping cough) are now very rare (3% of the deaths of children under 5 years during the period 1985–1989). Although the risks of dying from diarrhoea or acute respiratory infections are much lower than in other rural areas of Senegal, these are still the main causes of deaths (33% and 19% of deaths after 1 month of age). Malaria, despite its high morbidity during the rainy season, causes few deaths (4%). This reflects the success of the health education programme promoting chemoprophylaxis and early treatment of fever cases. Mlomp is one example of an African rural area where the provision of well-organized health services at a reasonable cost has produced a dramatic decline in child mortality

Lower mortality for female-female twins than male-male and male-female twins in rural Senegal

Twins have been registered prospectively for 12–22 years in 42 small villages in the Bandafassi area of Eastern Senegal. We studied 98 pairs of twins to test whether twins in opposite-sex pairs have higher postneonatal mortality than same-sex twins. Neonatal mortality for twins was 41.3%; mortality for infants and for children under age 5 years was 53.0% and 66.8%, respectively. Neonatal mortality was identical for same-sex and opposite-sex twin pairs, but much higher for boys than girls [relative risk = 1.8; 95% confidence interval (CI) = 1.2–2.6]. There was clustering of double neonatal deaths for all types of twins. In the postneonatal period, female-female twins had lower mortality than other twin types. Twins had higher postneonatal mortality as long as the co-twin was alive [mortality rate ratio (MR) = 2.6; 95% CI = 1.0–6.7]. Girls had excess mortality when the co-twin was of the opposite sex (MR = 4.3; 95% CI = 1.2–15.3), whereas there was no difference for boys. In conclusion, contact with a co-twin of the opposite sex increased child mortality for female twins. Our data are not sufficient to determine whether this difference is specific for girls or applies to boys as well

L'évolution des causes de décès d'enfants en Afrique : une étude de cas au Sénégal avec la méthode d'autopsie verbale

Dans les pays où les malades sont rarement examinés par un médecin et où les registres médicaux sont insuffisants pour déterminer les causes de la mortalité, force est de recourir à d'autres sources pour obtenir ces informations. Une méthode de collecte d'informations sur les causes de décès par des non-médecins a été mise au point dans plusieurs pays en développement, dite méthode des "autopsies verbales" : après chaque décès, une enquête est effectuée auprès des familles, à partir de questionnaires standardisés portant sur les symptômes et l'histoire de la maladie qui a conduit au décès; Nous avons appliqué cette méthode à tous les décès d'enfants de moins de 5 ans, sur une période de 10 ans (1984-1993) dans la zone d'étude de Bandafassi, au Sénégal Oriental, où une population d'environ 8000 habitants est suivie depuis 25 ans par enquête démographique à passage annuel. Bien que le pourcentage de décès dont la cause demeure indéterminée par cette méthode reste élevé (de 30 à 40%), celle-ci nous a permis de détecter les maladies les plus meurtrières dans chaque classe d'âge et les principales variations des causes de la mortalité selon des facteurs démographiques (le sexe et l'âge) ou climatiques (la saison du décès). Enfin, la répétition de ces enquêtes chaque année sur 10 ans donne une idée des évolutions des causes de décès les plus importantes, ce qui permet d'évaluer le succès des programmes sanitaires mis en oeuvre, ou d'orienter ceux à venir. (Résumé d'auteur

Atrial fibrillation ablation techniques

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