The effects of covariate adjustment in generalized linear models

Results from classical linear regression regarding the effects of covariate adjustment, with respect to the issues of confounding, the precision with which an exposure effect can be estimated, and the efficiency of hypothesis tests for no treatment effect in randomized experiments, are often assumed to apply more generally to other types of regression models. In this paper results pertaining to several generalized linear models involving a dichotomous response variable are given, demonstrating that with respect to the issues of confounding and precision, for models having a linear or log link function the results of classical linear regression do generally apply, whereas for other models, including those having a logit, probit, log-log, complementary log-log, or generalized logistic link function, the results of classical linear regression do not always apply. It is also shown, however, that for any link function, covariate adjustment results in improved efficiency of hypothesis tests for no treatment effect in randomized experiments, and hence that the classical linear regression results regarding efficiency do apply for all models having a dichotomous response variable.     

关于层次分析法的数值试验

通过对层次分析法进行数值模拟,证实了次序性程度不仅对评价结果存在着显著的影响,而且也与一致性指标存在着密切的关系,同时也证实了标度精度不足是导致多种标度并存的原因,并建议采用适当的标度精度,这一观点与Saaty是一致的。实验结果还清楚地表明,单纯使用一致性指标判定一个矩阵好坏是不够的,应该辅助以其它指标。     

宇航精密仪表及零件用LY12铝合金的尺寸稳定性

综述了宇航精密仪表及零件用LY12铝合金的尺寸稳定性,分析了影响尺寸稳定性的因素,提出了改善尺寸稳定性的途径.     

Improving precision and power in randomized trials with a two-stage study design: Stratification using clustering method

In a randomized controlled trial (RCT), it is possible to improve precision and power and reduce sample size by appropriately adjusting for baseline covariates. There are multiple statistical methods to adjust for prognostic baseline covariates, such as an ANCOVA method. In this paper, we propose a clustering-based stratification method for adjusting for the prognostic baseline covariates. Clusters (strata) are formed only based on prognostic baseline covariates, not outcome data nor treatment assignment. Therefore, the clustering procedure can be completed prior to the availability of outcome data. The treatment effect is estimated in each cluster, and the overall treatment effect is derived by combining all cluster-specific treatment effect estimates. The proposed implementation of the procedure is described. Simulations studies and an example are presented.     

Ranked set sampling with unequal samples for skew distributions

A ranked set sampling procedure with unequal samples for positively skew distributions (RSSUS) is proposed and used to estimate the population mean. The estimators based on RSSUS are compared with the estimators based on ranked set sampling (RSS) and median ranked set sampling (MRSS) procedures. It is observed that the relative precisions of the estimators based on RSSUS are higher than those of the estimators based on RSS and MRSS procedures.     

基于FPGA的高频等精度频率计设计与实现

文章介绍了等精度频率计误差分析和实现原理,在Altera新一代FPGA/PLD开发软件QuartusⅡ 中运用硬件描述语言Verilog HDL编程,通过单片机控制EP1 C12Q240I7芯片实现等精度频率计的设计,频率计可通过分频测量800 MHZ～1 400 MHZ之间的高频信号频率,大大提高了测量精度,实验证明测量精度为0.000 03％以下.     

试论社会主义核心价值体系的定位传播

定位传播是强化社会主义核心价值体系宣传实效的基本途径。定位传播注重受众细分理论的运用,强调根据目标受众的思想特性和价值观念,在社会主义核心价值体系中选择贴近目标受众生活和实际的专题内容开展传播,突出针对性,讲究精准度,扩大社会主义核心价值体系的影响力。     

Sample size determination for estimating multivariate process capability indices based on lower confidence limits

With the advent of modern technology, manufacturing processes have become very sophisticated; a single quality characteristic can no longer reflect a product's quality. In order to establish performance measures for evaluating the capability of a multivariate manufacturing process, several new multivariate capability (NMC) indices, such as NMC _p and NMC _pm , have been developed over the past few years. However, the sample size determination for multivariate process capability indices has not been thoroughly considered in previous studies. Generally, the larger the sample size, the more accurate an estimation will be. However, too large a sample size may result in excessive costs. Hence, the trade-off between sample size and precision in estimation is a critical issue. In this paper, the lower confidence limits of NMC _p and NMC _pm indices are used to determine the appropriate sample size. Moreover, a procedure for conducting the multivariate process capability study is provided. Finally, two numerical examples are given to demonstrate that the proper determination of sample size for multivariate process indices can achieve a good balance between sampling costs and estimation precision.     

熔模铸造技术专利申请状况分析

本文对熔模铸造专利从中国专利申请量分布、申请人分布、技术发展特点等方面进行了检索、统计分析,以帮助我国企业了解现有熔模铸造技术水平、研发动向等,为制定相关研发策略以及相应的专利策略提供参考。     

预防机械加工类专业职业性肌肉骨骼疾患的措施

通过对职业性肌肉骨骼疾患概念、机械加工类专业职业性肌肉骨骼疾患的国内外研究现状和常见职业性肌肉骨骼疾患的阐述,以及对其病因的分析,提出中等专业学校体育预防机械加工类专业职业性肌肉骨骼疾患的措施及建议。