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部分数据缺失时倾向得分的估计与使用AI 解读

Investigators in observational studies have no control over treatment assignment. As a result, large differences can exist between the treatment and control groups on observed covariates, which can lead to badly biased estimates of treatment effects. Propensity score methods are an increasingly popular method for balancing the distribution of the covariates in the two groups to reduce this bias; for example, using matching or subclassification, sometimes in combination with…

医学研究的统计方法AI 解读

Statistics in medicine the design of medical investigations - clinical trials and other methods measurement in medicine statistical inference regression analysis repeated measures analysis of variance and the analysis of covariance crossover designs the analysis of survival data multivariate data and principal components analysis statistical methods for classification - cluster analysis and assignment techniques time series analysis the analysis of observational techniques.…

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总体峰度变化下位置估计量的稳健性AI 解读

We investigate the robustness of various estimators of the mean for two families of symmetric distributions (exponential power and t) indexed by the kurtosis γ and Hogg's (1972) measure of tail thickness Q. For fixed γ or Q, the optimal estimator for one family is often inefficient for the other family. Furthermore, over various ranges of γ or Q some common estimators (e.g., the median) are efficient only for one family. However, other estimators (e.g., some trimmed means…

总体峰度变化下位置估计量的稳健性AI 解读

We investigate the robustness of various estimators of the mean for two families of symmetric distributions (exponential power and t) indexed by the kurtosis γ and Hogg's (1972) measure of tail thickness Q. For fixed γ or Q, the optimal estimator for one family is often inefficient for the other family. Furthermore, over various ranges of γ or Q some common estimators (e.g., the median) are efficient only for one family. However, other estimators (e.g., some trimmed means…

完整样本或尾部删失样本下 Logistic 分布参数的线性估计AI 解读

In this paper we present the asymptotically best linear unbiased estimators for the location and scale parameters of the logistic distribution based on samples where there may be Type 2 censoring in the tails. Given the amount of censoring, the weights of the estimators can be expressed in simple closed forms. Comparisons of these with the best linear unbiased estimators and the Cramer-Rao lower bounds demonstrate that they have good efficiency even for small samples.

完整或尾部删失样本下 Logistic 分布参数的线性估计AI 解读

In this paper we present the asymptotically best linear unbiased estimators for the location and scale parameters of the logistic distribution based on samples where there may be Type 2 censoring in the tails. Given the amount of censoring, the weights of the estimators can be expressed in simple closed forms. Comparisons of these with the best linear unbiased estimators and the Cramer-Rao lower bounds demonstrate that they have good efficiency even for small samples.

Geary 正态性检验的功效AI 解读

The results of an extensive simulation study investigating the power of Geary's a test for normality are summarized. While there appears to be no specific situation where Geary's test clearly and for practical purposesdominates all other tests of normality, it still has good power properties. This coupled with its computational simplicity make it still a possibly useful test.

Geary 正态性检验的功效AI 解读

The results of an extensive simulation study investigating the power of Geary's a test for normality are summarized. While there appears to be no specific situation where Geary's test clearly and for practical purposesdominates all other tests of normality, it still has good power properties. This coupled with its computational simplicity make it still a possibly useful test.

√b1 零假设分布的若干近似方法AI 解读

A comparative study of approximations to the null distribution of √ b1 is given for small sample sizes, i. e. n ≤ 35. The approximations studied are the approximations by the normal distribution, the Johnson SU distributions, the t or Pearson Type VII distributions, the Cornish-Fisher expansions using moments up to the eighth, with and without Geary's adjustment, and, finally, Monte-Carlo simulations. For the usual levels of significance all the approximations, except the…

正态分布标准差的一类简单线性估计量AI 解读

A class of simple linear estimators of the standard deviation of the normal distribution is considered. They are based on the differences between the sums of the observations in the tails of the ordered sample. For normal distributions they are asymptotically unbiased and possess good efficiency—even for small samples. Also for a wide range of non-normal distributions they are reasonably robust asymptotically.

适用于中等与大样本的综合正态性检验AI 解读

We present a test of normality based on a statistic D which is up to a constant the ratio of Downton's linear unbiased estimator of the population standard deviation to the sample standard deviation. For the usual levels of significance Monte Carlo simulations indicate that Cornish-Fisher expansions adequately approximate the null distribution of D if the sample size is 50 or more. The test is an omnibus test, being appropriate to detect deviations from normality due either…