265 research outputs found
Structural components in functional data.
No full textAnalyzing functional data often leads to finding common factors, for which functional principal component analysis proves to be a useful tool to summarize and characterize the random variation in a function space. The representation in terms of eigenfunctions is optimal in the sense of L2 approximation. However, the eigenfunctions are not always directed towards an interesting and interpretable direction in the context of functional data and thus could obscure the underlying structure. To overcome such difficulty, an alternative to functional principal component analysis is proposed that produces directed components which may be more informative and easier to interpret. These structural components are similar to principal components, but are adapted to situations in which the domain of the function may be decomposed into disjoint intervals such that there is effectively independence between intervals and positive correlation within intervals. The approach is demonstrated with synthetic examples as well as real data. Properties for special cases are also studied
THE AUDIT OF RECRUITMENT, SELECTION AND INTEGRATION OF THE HUMAN RESOURCES
No full textThe most well known category and also the most important is the one referring to the recruitment and selection of staff. Here, a lot of issues of legal nature may occur within the organization.This part refers to obtaining and assessing the qualified canAudit ,Recruitment,Selection,Integration, Human Resources
Une analyse comparative de la durée moyenne de vie restante chez les personnes âgées de 80 ans et plus
No full textLa durée moyenne de vie d'une population est l'un des principaux indicateurs de l'état de santé, en¦tous cas celui qui est le plus utilisé. Cette durée moyenne peut être estimée de plusieurs façons,¦chacune basée sur une table de mortalité différente. La plus répandue est celle calculée avec les¦tables de mortalité du moment. Une deuxième approche est la table de génération, qui estime la¦durée moyenne de vie des générations éteintes au moment de l'analyse. Enfin, la troisième approche¦est une table de cohorte (de survie), construite à partir d'individus suivis depuis un recensement.¦Cette dernière possibilité est récemment disponible en Suisse avec l'appariement des données¦fédérales provenant du recensement et de la mortalité, permettant une comparaison des durées¦moyennes de vie estimées selon trois approches différentes (moment, génération, cohorte). Vu les¦débats actuels sur l'accroissement de la longévité et la diminution rapide de la mortalité chez les¦personnes âgées et très âgées, nous nous sommes concentrés sur la comparaison des durées¦moyennes de vie chez les personnes de plus de 80 ans. Notre étude montre que la durée moyenne¦de vie issues des tables de cohorte est inférieure à celle estimée à partir des tables de génération.¦L'espérance de vie du moment est également en‐dessous de celle estimée par les tables de¦génération, mais dans une moindre proportion. Cette étude est la première à ce jour à comparer les¦tables de cohorte, de génération et du moment en Suisse
Hypothalamic and gonadal components of hypogonadism in boys with Prader-Labhart-Willi syndrome
No full textCONTEXT: The specific form of hypogonadism in Prader-Labhart-Willi syndrome (PWS), central or peripheral, remains unexplained.
OBJECTIVES: The objectives of this study were to investigate the cause of hypogonadism in PWS and determine whether human chorionic gonadotropin (hCG) treatment can restore pubertal development.
DESIGN: This was a clinical follow-up study, divided into two samples, over a duration of 1.5 and 4.5 yr.
PATIENTS: Eight male infants and six peripubertal boys (age at start of observation, 0.06-0.93 and 8.1-10.8 yr, respectively) with genetically confirmed PWS were studied.
INTERVENTION: hCG (500-1500 U twice weekly) was given from age 13.5 yr to the present.
MAIN OUTCOME MEASURES: Serum FSH, LH, inhibin B, and testosterone levels and pubertal development were the main outcome measures.
RESULTS: Infants with PWS presented normal LH (2.3 +/- 0.7 U/liter) and testosterone (2.5 +/- 0.9 nmol/liter) levels (mean +/- sem at 5 months) compared with the reference range. However, two thirds of the boys displayed cryptorchidism. Inhibin B levels were at the lowest level of the normal range and decreased significantly between infancy and puberty (at 13 yr, 72 +/- 17 pg/ml), whereas FSH secretion increased (9.9 +/- 2.6 U/liter). Pubertal maturation stopped at an average bone age of 13.9 yr. hCG therapy increased testosterone (11 +/- 2 nmol/liter) and reduced FSH (at 16 yr, 1.1 +/- 0.9 U/liter) levels. Testicular volume (5.6 +/- 1 ml) and inhibin B (26.5 +/- 11.9 pg/ml) remained low.
CONCLUSION: Children with PWS display a specific form of combined hypothalamic (low LH) and peripheral (low inhibin B and high FSH) hypogonadism, suggesting a primary defect in Sertoli and/or germ cell maturation or an early germ cell loss. hCG therapy stimulates testosterone production and virilization
On distribution-free tests for the multivariate two-sample location-scale model
No full textIn this paper, we propose simple exact procedures for testing both a location shift and/or a scale change between two multivariate distributions. Our tests are strictly distribution-free and can be made either scale invariant or rotation invariant. Our approach combines a generalization of the Wilcoxon test based on projections of the data onto the first principal component, a generalization of the Siegel–Tukey test based on the concept of data depth, and a bivariate test for the location problem proposed by K. V. Mardia (1967, J. Roy. Statist. Soc. Ser. B29, 320–342). In addition, we show that the limiting null distribution of a test statistic proposed by R. Y. Liu and K. Singh (1993, J. Amer. Statist. Assoc.88, 252–260) does not depend on the depth considered
A mixed approach for proving non-inferiority in clinical trials with binary endpoints
No full textWhen a new treatment is compared to an established one in a randomized clinical trial, it is standard practice to statistically test for non-inferiority rather than for superiority. When the endpoint is binary, one usually compares two treatments using either an odds-ratio or a difference of proportions. In this paper, we propose a mixed approach which uses both concepts. One first defines the non-inferiority margin using an odds-ratio and one ultimately proves non-inferiority statistically using a difference of proportions. The mixed approach is shown to be more powerful than the conventional odds-ratio approach when the efficacy of the established treatment is known (with good precision) and high (e.g. with more than 56% of success). The gain of power achieved may lead in turn to a substantial reduction in the sample size needed to prove non-inferiority. The mixed approach can be generalized to ordinal endpoints
Marginal adaptation in vitro and clinical outcome of Class V restorations
No full textOBJECTIVES: We examined the correlation between the quantitative margin analysis of two laboratory test methods (Berlin, Zurich) and the clinical outcome in Class V restorations. METHODS: Prospective clinical studies with an observation period of at least 18 months were searched in the literature, for which laboratory data were also available. The clinical outcome variables were retention loss, marginal discoloration, detectable margins and secondary caries. Forty-four clinical studies matched the inclusion criteria, including 34 adhesive systems for which laboratory data were also present. For both laboratory test methods and the clinical studies, an index was formulated to better compare the in vitro and in vivo results. Linear mixed models which included a random study effect were calculated. As most clinical data were available for 12 and 24 months, the main analysis was restricted to these recall intervals. RESULTS: The comparative analysis revealed a weak correlation between the clinical index and both in vitro indices. The correlation was statistically significant for the Berlin method but not for the Zurich method and only present if studies were compared which used the same composite in the in vitro and in vivo study. When defining specific cut-off values, the prognosis for the good clinical performance of an adhesive system based on in vitro results was 78% (Berlin) or 100% (Zurich). For poor performance it was 67% and 60%, respectively. No correlation was found between both in vitro methods. SIGNIFICANCE: The surrogate parameter "marginal adaptation" of restorations placed in extracted teeth has a mediocre value to predict the clinical performance of an adhesive system in cervical cavities. The composite is an important factor for a successful prediction. The comparison between in vitro/in vivo is sometimes hampered by the great variability of clinical results on the same adhesive system
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