Statistical Inference Based on Pooled Data: A Moment-Based Estimating Equation Approach

We consider statistical inference on parameters of a distribution when only pooled data are observed. A moment-based estimating equation approach is proposed to deal with situations where likelihood functions based on pooled data are difficult to work with. We outline the method to obtain estimates and test statistics of the parameters of interest in the general setting. We demonstrate the approach on the family of distributions generated by the Box-Cox transformation model, and, in the process, construct tests for goodness of fit based on the pooled data.     

Easy-to-construct confidence bands for comparing two simple linear regression lines

This paper shows how to construct confidence bands for the difference between two simple linear regression lines. These confidence bands provide directly the information on the magnitude of the difference between the regression lines over an interval of interest and, as a by-product, can be used as a formal test of the difference between the two regression lines. Various different shapes of confidence bands are illustrated, and particular attention is paid towards confidence bands whose construction only involves critical points from standard distributions so that they are consequently easy to construct.     

水蒸气钝化裂化催化剂工艺条件的探讨

对共Y-15裂化催化剂在模拟工业条件下进行了不同温度、压力和时间的水蒸气处理,考察了其钝化效果,将高温水蒸气的钝化效果与锑钝化剂的钝化效果进行了比较.结果表明,前者的钝化效果优于后者;经高温水蒸气钝化后的裂化催化剂能在微活性不显著降低的前提下,使氢气产率、焦炭产率显著降低.     

PES-C,(PP/Bis-T)PES的次级松驰与转变

描述了酚酞型聚芳醚砜(PES-C)的次级松驰和转变与其结构的关系.TBA和动态力学实验结果表明:PES-C及其共聚物(PP/Bis-T)PES分别在0～50℃和-100℃附近呈现出两个次级松驰峰;双酚T单元的引入导致了PES-C在0～50℃之间的次级松驰位置改变.证实了Cardo侧基的存在对-100℃的次级松驰有较大的贡献.     

圆锥轴受扭时静、动力的传递矩阵法求解

本文提出了圆锥轴受扭时静、动力的传递矩阵。该方法简便实用,适于工程技术人员在微机上应用。     

赤松花粉毒性及对大白鼠细胞染色体致畸的测试

对赤松花粉进行了大白鼠急性毒性及骨髓细胞染色体的致畸变测试.结果表明,赤松花粉的LD_(50)>30000mg/kg,无明显的致畸变效应.     

光纤转角、位移传感器的理论研究

提出了“光纤桥”新概念,利用“光纤桥”构成了测量转角、位移的光纤传感器。利用准高斯光束假设,详细地分析、计算了系统参数对传感器性能的影响,理论上预见了测角精度可达1”,测角范围±6′。     

电视机自动增益控制电路动态特性测量

本文提出一种电视机自动增益控制电路动态特性简易测量方法.按照此法,只需在待测电视机前加一级可调衰减器,就能用常用电子仪器测出自动增益控制电路的动态特性,并以此为依据改善电视机相关电路的性能.     

区域主导产业评价指标与数学模型

以现有研究成果为基础,建立了区域主导产业评价指标体系;基于灰色聚类的思想,提出了评价区域主导产业优度的数学模型-定权聚类评估模型,并对河南省武陟县工业主导产业选择进行了实证研究。     

Influence of human immunodeficiency virus infection on neurological impairment: an analysis of longitudinal binary data with informative drop-out

A study to investigate the human immunodeficiency virus (HIV) status on the course of neurological impairment, conducted by the HIV Center at Columbia University, followed a cohort of HIV positive and negative gay men for 5 years and assessed the presence or absence of neurological impairment every 6 months. Almost half of the subjects dropped out before the end of the study for reasons that might have been related to the missing neurological data. We propose likelihood-based methods for analysing such binary longitudinal data under informative and non-informative drop-out. A transition model is assumed for the binary response, and several models for the drop-out processes are considered which are functions of the response variable (neurological impairment). The likelihood ratio test is used to compare models with informative and non-informative drop-out mechanisms. Using simulations, we investigate the percentage bias and mean-squared error (MSE) of the parameter estimates in the transition model under various assumptions for the drop-out. We find evidence for informative drop-out in the study, and we illustrate that the bias and MSE for the parameters of the transition model are not directly related to the observed drop-out or missing data rates. The effect of HIV status on the neurological impairment is found to be statistically significant under each of the models considered for the drop-out, although the regression coefficient may be biased in certain cases. The presence and relative magnitude of the bias depend on factors such as the probability of drop-out conditional on the presence of neurological impairment and the prevalence of neurological impairment in the population under study.