日期精度：到日 2273 篇 · 到月 7743 篇 · 到年 0 篇
二维凸密度轮廓的估计
If a density in two dimensions has a convex contour containing probability α, the contour may be estimated from a sample by finding the convex polygon of smallest area containing a proportion α of the sample points. An algorithm for finding a particular contour is given that takes O(n 2) space and O(n 3) time for n sample points.
正态近似准确性的评估
The widespread applicability and use of normal approximations creates a need for methods for assessing their accuracy in an operational fashion. In this article, two new methods are proposed and exemplified. These new methods are based on a comparison of the level curves of an exact likelihood with the level curves of the usual normal approximation to it and on a comparison of selected line integrals of an exact density and a normal approximation to it. The operational…
估计资本支出的目的抽样与随机抽样方案比较
This article reports results of a large-scale study of various sampling strategies. Conventional sampling strategies are compared with model-based strategies on data from over 12,000 businesses included in the annual Manufacturing Census of the Australian Bureau of Statistics. The study has been designed to replicate the quarterly Survey of Capital Expenditure. The results show that for the given data a stratified sample consisting of units with the largest values of the…
基于多个分层样本的估计及多抽样框调查应用
In this article, a new method for producing estimates from a multiple frame survey is presented. The discussion in this article is restricted to sample designs in which a stratified simple random sample is selected independently from each frame. The estimation technique outlined, however, can be applied to more complex sample designs. It is assumed that units selected in more than one sample can be identified. This estimation technique is based on the fact that a multiple…
用线性秩统计量比较多个总体
There are many nonparametric tests available for the analysis of k independent samples. For example, the Kruskal—Wallis test (Wilcoxon rank sum test when k = 2) is widely used for detecting location differences, and Mood or Ansari—Bradley or Sigel—Tukey rank statistics are often suggested for detecting scale differences. If more general alternatives are of interest, then one can use omnibus tests such as the generalized Kolmogorov—Smirnov and Cramér—von Mises statistics [see…
Logistic 回归中的异常值与残差分布
Detection of outliers and other diagnostics based on residuals have gained widespread use in linear regression. Logistic regression has been both blessed and hindered by this development. Certainly logistic regression requires procedures to detect global and local model weaknesses. Thus the wealth of work done in linear regression provides guides and suggestions that may, with care and ingenuity, be applied to logistic regression. Several innovative attempts in this…
广义线性模型中的残差
Generalized linear models are regression-type models for data not normally distributed, appropriately fitted by maximum likelihood rather than least squares. Typical examples are models for binomial or Poisson data, with a linear regression model for a given, ordinarily nonlinear, function of the expected values of the observations. Use of such models has become very common in recent years, and there is a clear need to study the issue of appropriate residuals to be used for…
连续协变量分类对生存时间比较的影响
The variance of the estimated hazard ratio between two groups when there is one categorized continuous gamma-distributed covariate is derived using exponential and Weibull regression models and asymptotic theory. Categorizing a continuous covariate increases the variance of the estimated hazard ratio and decreases the efficiency of the analysis. The efficiency of categorization is studied as a function of the strength of the relation between survival time and the covariate,…
比例趋势检验中历史对照信息的纳入
The testing of chemicals for carcinogenic activity in lifetime rodent bioassays has produced a large amount of data on a few strains of mice and rats. Because of the use of fixed protocols in repeated experiments, the opportunity presents itself for using this historical data in the analysis of a current experiment. What has been considered is the statistical incorporation of the historical control data into the current control group to increase the power of the test. This…
对异常值稳健的有限总体估计
Outliers in sample data are a perennial problem for applied survey statisticians. Moreover, it is a problem for which traditional sample survey theory offers no real solution, beyond the sensible advice that such sample elements should not be weighted to their fullest extent in estimation. Sample outliers can be identified as of two basic types. Here we are concerned with the first type, which may conveniently be termed representative outliers. These are sample elements with…
基尼系数与贫困指数：若干协调关系
Poverty is usually defined as the extent to which individuals in a society or community fall below a minimal acceptable standard of living. An index of poverty is generally based on the proportion (α) of the poor people and their income distribution through the income gap ratio (β) (i.e., the average income gap of the poor people from the poverty line ω, taken as a ratio to ω itself) and other measures of income inequalities. In this context, the well-known Gini coefficient…