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1.
When a candidate predictive marker is available, but evidence on its predictive ability is not sufficiently reliable, all‐comers trials with marker stratification are frequently conducted. We propose a framework for planning and evaluating prospective testing strategies in confirmatory, phase III marker‐stratified clinical trials based on a natural assumption on heterogeneity of treatment effects across marker‐defined subpopulations, where weak rather than strong control is permitted for multiple population tests. For phase III marker‐stratified trials, it is expected that treatment efficacy is established in a particular patient population, possibly in a marker‐defined subpopulation, and that the marker accuracy is assessed when the marker is used to restrict the indication or labelling of the treatment to a marker‐based subpopulation, ie, assessment of the clinical validity of the marker. In this paper, we develop statistical testing strategies based on criteria that are explicitly designated to the marker assessment, including those examining treatment effects in marker‐negative patients. As existing and developed statistical testing strategies can assert treatment efficacy for either the overall patient population or the marker‐positive subpopulation, we also develop criteria for evaluating the operating characteristics of the statistical testing strategies based on the probabilities of asserting treatment efficacy across marker subpopulations. Numerical evaluations to compare the statistical testing strategies based on the developed criteria are provided. 相似文献
2.
提出了一种基于小波变换的管理数据处理方法,把公司管理上的数据看成一个非平稳的时间序列,利用小渡函数将该时间序列分解到不同的频率通道上,然后将分解后的信号当作近似的平稳时间序列,用一些传统的统计方法进行预测,同时对中国足球彩票若干期的销售量数据进行了处理和预测,并将结果与实际销量以及用传统的AR模型的预测值进行了比较。 相似文献
3.
非统计专业统计学教育刍议 总被引:1,自引:0,他引:1
针对非统计专业统计学教育目前存在的问题,阐述了提高对统计学重要性的认识是保证统计教学效果的前提;统计学教学环节的改革是提高教学效果的重要保证;统计教师的业务素质是提高统计教学效果的关键。 相似文献
4.
Children may be more susceptible to toxicity from some environmental chemicals than adults. This susceptibility may occur during narrow age periods (windows), which can last from days to years depending on the toxicant. Breathing rates specific to narrow age periods are useful to assess inhalation dose during suspected windows of susceptibility. Because existing breathing rates used in risk assessment are typically for broad age ranges or are based on data not representative of the population, we derived daily breathing rates for narrow age ranges of children designed to be more representative of the current U.S. children's population. These rates were derived using the metabolic conversion method of Layton (1993) and energy intake data adjusted to represent the U.S. population from a relatively recent dietary survey (CSFII 1994–1996, 1998). We calculated conversion factors more specific to children than those previously used. Both nonnormalized (L/day) and normalized (L/kg-day) breathing rates were derived and found comparable to rates derived using energy estimates that are accurate for the individuals sampled but not representative of the population. Estimates of breathing rate variability within a population can be used with stochastic techniques to characterize the range of risk in the population from inhalation exposures. For each age and age-gender group, we present the mean, standard error of the mean, percentiles (50th, 90th, and 95th), geometric mean, standard deviation, 95th percentile, and best-fit parametric models of the breathing rate distributions. The standard errors characterize uncertainty in the parameter estimate, while the percentiles describe the combined interindividual and intra-individual variability of the sampled population. These breathing rates can be used for risk assessment of subchronic and chronic inhalation exposures of narrow age groups of children. 相似文献
5.
Pierre Legendre François-Joseph Lapointe 《Australian & New Zealand Journal of Statistics》2004,46(4):615-629
A test of congruence among distance matrices is described. It tests the hypothesis that several matrices, containing different types of variables about the same objects, are congruent with one another, so they can be used jointly in statistical analysis. Raw data tables are turned into similarity or distance matrices prior to testing; they can then be compared to data that naturally come in the form of distance matrices. The proposed test can be seen as a generalization of the Mantel test of matrix correspondence to any number of distance matrices. This paper shows that the new test has the correct rate of Type I error and good power. Power increases as the number of objects and the number of congruent data matrices increase; power is higher when the total number of matrices in the study is smaller. To illustrate the method, the proposed test is used to test the hypothesis that matrices representing different types of organoleptic variables (colour, nose, body, palate and finish) in single‐malt Scotch whiskies are congruent. 相似文献
6.
7.
In this paper we discuss a new theoretical basis for perturbation methods. In developing this new theoretical basis, we define the ideal measures of data utility and disclosure risk. Maximum data utility is achieved when the statistical characteristics of the perturbed data are the same as that of the original data. Disclosure risk is minimized if providing users with microdata access does not result in any additional information. We show that when the perturbed values of the confidential variables are generated as independent realizations from the distribution of the confidential variables conditioned on the non-confidential variables, they satisfy the data utility and disclosure risk requirements. We also discuss the relationship between the theoretical basis and some commonly used methods for generating perturbed values of confidential numerical variables. 相似文献
8.
Summary Weak disintegrations are investigated from various points of view. Kolmogorov's definition of conditional probability is critically
analysed, and it is noted how the notion of disintegrability plays some role in connecting Kolmogorov's definition with the
one given in line with de Finetti's coherence principle. Conditions are given, on the domain of a prevision, implying the
equivalence between weak disintegrability and conglomerability. Moreover, weak sintegrations are characterized in terms of
coherence, in de Finetti's sense, of, a suitable function. This fact enables us to give, an interpretation of weak disintegrability
as a form of “preservation of coherence”. The previous results are also applied to a hypothetical inferential problem. In
particular, an inference is shown to be coherent, in the sense of Heath and Sudderth, if and only if a suitable function is
coherent, in de Finetti's sense.
Research partially supported by: M.U.R.S.T. 40% “Problemi di inferenza pura”. 相似文献
9.
Jan F. M. Raes 《Statistics and Computing》1992,2(2):55-62
A decade of research into the applications of artificial intelligence in statistics has finally resulted in the appearance of commercially available statistical expert systems. This paper takes a closer look at two of these systems, which are now commercially available on microcomputers, and shows what knowledge they actually contain and how they operate. It is concluded that although the technology and concepts that drive these systems could still benefit from further improvement, the real challenge lies in defining and constructing the statistical knowledge and strategy that should be incorporated and in presenting the results to the user's full advantage. 相似文献
10.
本科生入学成绩与学业成绩的相关性分析 总被引:3,自引:0,他引:3
入学考试成绩是衡量生源质量的主要标准,本文对大学生的入学成绩与学业成绩的相关性进行了统计分析,旨在了解入学成绩对学业成绩的影响程度以及对提高学生学业成绩方面的启发。统计结果表明:不同入学成绩班级间的学分绩有差异;不同入学成绩学生的专业课成绩差异显著;不同入学成绩学生的四年总学分绩有极显著差异。 相似文献