Calculating the density and distribution function for the singly and doubly noncentral F

Simple, closed form saddlepoint approximations for the distribution and density of the singly and doubly noncentral F distributions are presented. Their overwhelming accuracy is demonstrated numerically using a variety of parameter values. The approximations are shown to be uniform in the right tail and the associated limitating relative error is derived. Difficulties associated with some algorithms used for exact computation of the singly noncentral F are noted.     

Design optimization using ANOVA

This paper describes the design optimization of a robot sensor used for locating 3-D objects employing the Taguchi method in a computer simulation scenario. The location information from the sensor is to be utilized to control the movements of an industrial robot in a 'pick-and-place' or assembly operation. The Taguchi method, which is based on the Analysis-of-Variance (ANOVA) approach, is utilized to improve the performance of the sensor over a wider operating range. A review of the Taguchi method is presented along with step-by-step implementation details to identify and optimize the design parameters of the sensor. The method allows us to gauge the impact of various interactions present in the sensor system exclusively and permits us to single out those factors that have a dominant influence on the overall performance of the sensor. The investigation suggests that the Taguchi method is a more structured and efficient approach for achieving a robust design compared with the classical full factorial design approach.     

Multistage methodologies for comparing several treatments with a control

We consider the problem of constructing a set of fixed-width simultaneous confidence intervals for the treatment-control differences of means for several independent normal populations with a common unknown variance. Taking c observations from the control population instead of the usual vector-at-a-time approach, purely sequential estimation methodology is developed and asymptotic second-order characteristics are provided. Brief remarks on the accelerated sequential and three-stage methodologies have been added. Next, with the help of simulations, performances of the purely sequential, accelerated sequential and three-stage estimation techniques are compared. Overall, the second-order asymptotics are found to provide useful approximations even for moderate sample sizes.     

Perfect simulation for correlated Poisson random variables conditioned to be positive

In this paper we present a perfect simulation method for obtaining perfect samples from collections of correlated Poisson random variables conditioned to be positive. We show how to use this method to produce a perfect sample from a Boolean model conditioned to cover a set of points: in W.S. Kendall and E. Thönnes (Pattern Recognition 32(9): 1569–1586, 1999), this special case was treated in a more complicated way. The method is applied to several simple examples where exact calculations can be made, so as to check correctness of the program using ²-tests, and some small-scale experiments are carried out to explore the behaviour of the conditioned Boolean model.     

Survival of adult,territorial Longtailed Wagtails Motacilla clara : The effects of environmental factors and individual covariates

The Longtailed Wagtail is a non-migratory African passerine that is confined exclusively to small, fast-flowing rivers in a largely arboreal environment. The breeding adults hold permanent, life-long, linear territories in their riverine habitat and this makes it easy to locate colour-marked birds. They are confiding by nature and permit close approach, often to less than 10 m, and this allows their unique permutations of colourrings to be read. Using data from the 21 year period, 1 August 1978 to 31 July 1999, of a dozen territories it has been shown that the breeding territories have not changed at all, even though there has been a continual, but slow turnover of territory holders. A total of 109 territorial adult birds were monitored for a total of 1121 bird-quarters and survival was estimated for each of four quarters in a year. The average survival rate is estimated at 68.8% yr -1 (95% confidence limits: 63.3% to 69.3%) and this is high for such a small bird (approximately 20 g) and there have been some remarkably long-lived individuals, e.g. 10 to 12 years. In this paper, a generalized linear model is built of the survival of territorial adults. It is shown that bigger birds have a higher survival rate and that there are seasonal differences in survival that are ascribable to the cost of breeding and possibly cost of moult. There is an underlying long-term quadratic trend in survival that is related to increasing environmental degradation and decreasing chemical pollution.     

Départ Des Enfants Et Contraction Des Familles D'Après Les Recensements Canadiens De 1971 Et De 1981

Censuses do not usually collect information on the departure of children and the consequent contraction of the family; however, they sometimes do include useful information on these phenomena and their evolution. On these questions this article presents a new use of the 1971 and 1981 Canadian censuses. From the analysis, it is estimated that the timing of children's departure from their family of origin was almost the same in 1981 as in 1971; median age at departure was identical: 20.5 for women and 22.3 for men. Broken families, more numerous than in the past, become contracted earlier than unbroken families; among unbroken families, the contraction phase started earlier in 1981 than in 1971 among large or medium-sized families while it began later among small families. The method developed here succeeds with the Canadian data in palliating the lack of surveys; it would be interesting to test it on data from other Western societies.     

论小说创作

如果可能,请别写小说.小说创作是一种非社会行为,一旦动笔,小说家会时刻为小说中的人物所困扰;而且,真正写起来,小说指南一类书籍并不管用.假如非写不可,那么,小说家需考虑是以情节为主还是以人物为主.如果以情节为主,小说家即在虚构的事情中间而非在所谓的真实生活中寻找人物的时候,抓住情节不放;如果以人物为主,那么,小说家则需对适于情节的某些特征加以强调,使人物在新环境中显得真实可信,从而赋予他们生命.小说家无论重情节抑或是重人物,都还要考虑以何种形式、何种风格呈现情节和人物的问题;当然,在优秀的小说家笔下,故事和人物本身会以最适合的形式出现.小说家应对形式、人物和语言保持一种敏锐的感觉.此外,小说家可能会对道德教诲产生迷恋.尽管应当通过作品给读者以教益,但是,真诚的艺术家并不能专注于说教.     

Passage a l'age adulte et mobilite spatiale

Starting with longitudinal data on two cohorts of women living in the Alpes-Maritimes in 1982 (a sample of 1,500 women in total) we try to establish the role of the spatial distribution of opportunities at a number of key stages in the life cycle: marriage, birth of first child, making professional use of qualifications, confrontation of a situation of professional risk and professional mobility during the years immediately following the completion of studies. The underlying hypothesis is that control of social location often depends on the control of spatial location.     

A cross-national look at married women's earnings dependency

Using the Luxembourg Income Study data we examine married women's dependency on their husbands' earnings in nine Western industrialized countries: Australia, Belgium, Canada, Finland, Germany, the Netherlands, Norway, Sweden, and the United States. When we examine the level and degree of dependency, and the labor force participation of married women across countries, the nine countries fall into the three clusters delineated in Esping-Andersen's welfare states typology. But when we examine the determinants of the dependency within each country, the clustering disappears. Wives' dependency increases with age, the presence of young children, and the number of children. It is reduced when wives' labor force participation and education are high relative to their husbands' and in families that rely more on unearned sources of income. The similarity of patterns across countries suggests that gender differences in the work-family nexus are deeply entrenched in all countries and continue even in the face of very active social policy to minize their effects. This is a revised version of a paper presented at the annual meeting of the American Sociological Association, August 1995, Washington DC. Her current research focuses on gender inequality and parents' time allocation between work and family. She conducts research on various aspects of family demography, including household and family characteristics, co-resident grandparent families, cohabitation, and child care. With Suzanne Bianchi, she is completing a research monograph on trends in the American family. Her research focuses on gender, work, and family issues.