医学等级资料相同秩次的校正

本文介绍了医学等级资料在进行秩和检验时,相同秩次如何需要校正以及正确的校正方法。为医学等级资料相同秩次的校正提供了一种简便、准确的统计方法。     

非参数Monotonic回归及其应用

本文针对不满足经典回归条件的一对变量，讨论并介绍了非参数Ｍｏｎｏｔｏｎｉｃ回归的建模思想、条件与方法。通过实例说明，Ｍｏｎｏｔｏｎｉｃ回归比最小二乘回归拟合误差小，模型精度高，计算简单，有一定的实用价值。     

两样本比较的秩和检验用T界值表的商榷——Wilcoxon秩和检验界值表的编制原理

对国内外几种工具表专著中,两样本比较的秩和检验用T界值表作了比较,其界值不尽一致。分析原因,是确定界值采用了两种不同的准则,以准则2的界值表更为合理。用实例介绍了秩和T的概率的计算方法。     

Multinomial probit estimation without nuisance parameters

A feasible multinomial estimation procedure is derived, which does not require parameterization of the elements in the covariance matrix. The estimation is carried out using a simulated expectation‐maximization algorithm, where the covariance structure is evaluated based on a set of score functions, while the structural coefficients are derived using standard multinomial probit (MNP) conditional on the given covariance structure. This methodology is demonstrated using a Monte Carlo simulation on both rank‐ordered and non‐ranked data, and on a real data set involving the choice of local residential telephone service. For limited finite samples, the procedure is shown to be superior to conventional MNP since it is faster, involves fewer parameters, and generates estimates with smaller variances.     

A Note on Power and Sample Size Calculations for the Kruskal–Wallis Test for Ordered Categorical Data

Although the Kruskal–Wallis test has been widely used to analyze ordered categorical data, power and sample size methods for this test have been investigated to a much lesser extent when the underlying multinomial distributions are unknown. This article generalizes the power and sample size procedures proposed by Fan et al. (2011 Fan , C. , Zhang , D. , Zhang , C. H. (2011). On sample size of the Kruskal-Wallis test with application to a mouse peritoneal cavity study. Biometrics 67:213–224.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) for continuous data to ordered categorical data, when estimates from a pilot study are used in the place of knowledge of the true underlying distribution. Simulations show that the proposed power and sample size formulas perform well. A myelin oligodendrocyte glycoprotein (MOG) induced experimental autoimmunce encephalomyelitis (EAE) mouse study is used to demonstrate the application of the methods.     

Weighted Rank Tests for Noninferiority Hypotheses Based on Paired Survival Times

Motivated by the design and analysis of a specific type of Phase II cancer clinical trials, we derive in this article a class of weighted rank tests for the testing of noninferiority hypotheses with a prespecified margin based on paired survival times. Monte Carlo simulations are performed to evaluate the performance of the proposed tests. Sample size calculation when these tests are used for the analysis is also discussed. Procedures developed are also applied to a Phase II clinical trial of metastatic breast cancer.     

Impaired arsenic metabolism in children during weaning

Background

Methylation of inorganic arsenic (iAs) via one-carbon metabolism is a susceptibility factor for a range of arsenic-related health effects, but there is no data on the importance of arsenic metabolism for effects on child development.

Aim

To elucidate the development of arsenic metabolism in early childhood.

Methods

We measured iAs, methylarsonic acid (MA) and dimethylarsinic acid (DMA), the metabolites of iAs, in spot urine samples of 2400 children at 18 months of age. The children were born to women participating in a population-based longitudinal study of arsenic effects on pregnancy outcomes and child development, carried out in Matlab, a rural area in Bangladesh with a wide range of arsenic concentrations in drinking water. Arsenic metabolism was evaluated in relation to age, sex, anthropometry, socio-economic status and arsenic exposure.

Results

Arsenic concentrations in child urine (median 34 μg/L, range 2.4-940 μg/L), adjusted to average specific gravity of 1.009 g/mL, were considerably higher than that measured at 3 months of age, but lower than that in maternal urine. Child urine contained on average 12% iAs, 9.4% MA and 78% DMA, which implies a marked change in metabolite pattern since infancy. In particular, there was a marked increase in urinary %MA, which has been associated with increased risk of health effects.

Conclusion

The arsenic metabolite pattern in urine of children at 18 months of age in rural Bangladesh indicates a marked decrease in arsenic methylation efficiency during weaning.     

上海市生产性农药中毒发病情况的综合评价

目的综合评价1997—2005年上海市生产性农药中毒发病情况,为农药中毒防控工作提供依据。方法用综合评价法之一的秩和比（RSR）法进行处理。并引入分比（SR）和经验权重系数（W’）对秩和比RSR进行校正。结果在1997—2005年这9年中,以2000、2005、1999年的生产性农药中毒发病情况较好。1997和1998年较差。逐年发病呈现波动性趋好趋势。结论按发病程度轻重,并给以权重的综合评价法对9年的农药中毒发病情况进行分析,评价全面,结果可靠。     

2007年西安市居民全死因监测分析

目的了解西安市居民死因分布特点及对寿命的影响,为综合防治提供依据。方法利用死亡率、构成比及潜在寿命损失（PYLL）,对我市2007年死因监测资料进行描述性统计分析。结果西安市2007年报告总死亡率为572．88／10万,前5位死因分别为：心脏病、恶性肿瘤、脑血管病、损伤和中毒、呼吸系统疾病,占全死因的78．91％;交通事故（机动车辆交通事故、机动车以外的运输事故）、意外跌落、意外中毒和自杀是损伤和中毒的主要死因,是造成该市居民“早死”及青壮年死亡的主要死因。结论慢性非传染性疾病在总死亡中的比例最高,是危害该市居民健康的主要死因,损伤和中毒是危害西安市青壮年健康的主要危险因素,因此,加强预防和控制慢性病是当务之急,同时政府应尽快把伤害纳入疾病预防控制规划。     

2005--2008年云南省居民死因监测分析

目的了解云南省疾病监测点居民死因分布特点,为综合防治提供依据。方法通过死亡率、构成比、潜在减寿年数（PYLL）、减寿率（PYLL率）等指标分析居民死亡和减寿的主要原因。结果2006--2008年云南省疾病监测点报告死亡人数39014例,死亡率564．40／10万（标化死亡率为578．62／10万）,男性高于女性;前5位死因顺位依次为呼吸系统疾病、损伤和中毒、脑血管病、恶性肿瘤、心脏病,占全死因的71．07％;呼吸系统疾病、损伤和中毒、恶性肿瘤是造成云南省疾病监测点居民寿命损失的主要疾病;自杀、意外跌落、机动车辆交通事故、其他意外事故和有害效应是损伤和中毒的主要死因。是造成监测点居民“早死”及青壮年死亡的主要死因。结论慢性非传染性疾病是构成监测点居民死亡的主要原因,损伤和中毒是构成监测点青壮年“早死”的主要原因。