The Effect of Methods for Handling Missing Values on the Performance of the MEWMA Control Chart

This article is concerned with the effect of the methods for handling missing values in multivariate control charts. We discuss the complete case, mean substitution, regression, stochastic regression, and the expectation–maximization algorithm methods for handling missing values. Estimates of mean vector and variance–covariance matrix from the treated data set are used to build the multivariate exponentially weighted moving average (MEWMA) control chart. Based on a Monte Carlo simulation study, the performance of each of the five methods is investigated in terms of its ability to obtain the nominal in-control and out-of-control average run length (ARL). We consider three sample sizes, five levels of the percentage of missing values, and three types of variable numbers. Our simulation results show that imputation methods produce better performance than case deletion methods. The regression-based imputation methods have the best overall performance among all the competing methods.     

On a Relation between Principal Components and Regression Analysis

A regression approach to principal component analysis is presented in this note. We provide an alternative interpretation of principal components that illustrates the relation between the extra sum of squares in regression analysis and the eigenvalues associated with the principal components.     

我国商业银行小额账户收费动因研究

2005年以来,我国主要商业银行相继出台了小额账户清理和收费措施,本文首先分析清理小额账户的直接动机,进而通过中美两国银行业数据进行比较,运用理论阐述和实证分析说明小额账户政策调整的深层次原因在于减小系统压力、改善银行收入结构和分散风险,并提出了小额账户收费改革中可能面临的问题及解决对策。     

欧拉函数φ（n）的两个估计式

探讨了当ｘ≥１，ｋ为负整数时，欧拉函数的ｋ次方和的估计式，并得到欧拉函数对数和的估计式，式中为素数，求和号下的ｐ过全体素数，，式中为素数，求和号下的ｐ过全体素数。     

L-函数的一个四次加权均值

利用特征和的性质及其解析方法讨论了DirichletL-函数的一个四次加权均值，得到一个加权均值分布的渐近公式。     

两类图的和数

研究了两类完全多部图的和数,证明了图K1,1,r和K1,1,1,r(r≥3)的和数分别是r和r 2.     

一类无平方因子数的k次方和

拓广了无平方因子数ｋ次方和的结果，得到一类无平方因子数ｋ次方和的估计式．     

英语教学中激发学生学习兴趣的探索

用言简意赅的语言多角度、多层次地结合教学实际对英语教学中字、词、句及篇章等教学进行了较为全面的具有实际指导作用的介绍 ,文章图文并茂 ,对英语的实际教学具有很强的借鉴作用     

运用离差最大化方法对影响区域经济发展因素的分析

分析了离差最大化方法的特点,通过实证表明,运用离差最大化方法在确定指标权重方面比较客观的优点,分析不同区域经济发展过程中的主要影响因素,可寻求制定区域经济发展对策与措施的客观依据。     

The RL2 chart versus the np chart for detecting upward shifts in fraction defective

The use of the np chart for monitoring fraction-defective is well-established, but there are a number of relatively simple alternatives based on run-lengths of conforming items. Here, the RL₂ chart, based on the moving sum of two successive conforming run-lengths, is investigated in order to provide SPC practitioners with clear-cut guidance on the comparative performance of these competing charts. Both sampling inspection and 100% inspection are considered here, and it is shown that the RL₂ chart can often be considerably more efficient than the np chart, but the comparative performance depends on the false-alarm rate used for the comparison. Graphs to aid parameter-choice for the RL₂ chart are also provided.