Standard Exponential Cure Rate Model with Informative Censoring

In this article, we consider the standard cure rate model proposed by Boag (1949 Boag , J. W. ( 1949 ). Maximum likelihood estimates of the proportion of patients cured by cancer therapy . J. Roy. Statist. Soc. B 11 : 15 – 53 . [Google Scholar]) and Berkson and Gage (1952 Berkson , J. , Gage , R. ( 1952 ). Survival curve for cancer patients following treatment . J. Amer. Statist. Assoc. 47 : 501 – 515 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). We present a new definition of informative censoring similar to Lawless (1982 Lawless , J. F. ( 1982 ). Statistical Models and Methods for Lifetime Data . New York : Wiley .[Crossref] , [Google Scholar]) and the corresponding likelihood function. Under informative censoring, we obtain the Fisher information matrix of the exponential standard cure rate model. We verify, with simulated data, the impact caused by informative censoring in the coverage probabilities and in the lengths of asymptotic confidence intervals of the parameters of interest. An example with real data is analyzed.     

Statistical Computing Software Reviews

This section is similar in organization to a Book Review section in other journals; however, software of interest to statisticians is the subject of review here. Emphasis is on software for microcomputers. Programs that operate only in larger mainframe computers will seldom receive review. Normally, producers of programs make a copy of their product available to the Section Editor, who then selects one or more persons to test the product and prepare a review.

Producers of computer software who wish to have their product reviewed are invited to contact the Section Editor, Professor Kenneth Berk, Department of Mathematics, 313 Stevenson Hall, Illinois State University, Normal, IL 61761.

Findings and opinions expressed in every review are solely those of the author. They should not be construed as reflecting endorsement of the product, or opinions held, by the American Statistical Association, nor is any warranty implied about any product reviewed.

STAN, Version II.0. David M. Allen. Available from Statistical Consultants, Inc., 462 E. High Street, Lexington, KY 40508. $300. Reviewed by Peter A. Lachenbruch     

Comparison of Confidence Intervals on Between Group Variance in Unbalanced Heteroscedastic One-Way Random Models

A computer algorithm for computing the alternative distributions of the Wilcoxon signed rank statistic under shift alternatives is discussed. An explicit error bound is derived for the numeric integration approximation to these distributions.

A nonparametric process control procedure in which the standard CUSUM procedure is applied to the Wilcoxon signed rank statistic is discussed. In order to implement this procedure, the distribution of the Wilcoxon statistic under shift of the underlying distribution from its point of symmetry needs to be computed. The average run length of the nonparametric and parametric CUSUM are compared.     

Comparison of One-Sided Tolerance Limits in Unbalanced One-Way Random Models

Cox's discrete logistic model was extended to the study of the life table by Thompson (1977) to handle grouped survival data. Inferences about the effect of grouping are studies byMonte Carlo methods. The results show that the effect of grouping is not substantial. This approach is applied to the grouped data on liver cancer. The computer program developed for grouped censored data with continuous and indicator covariates is of practical importance and is available fromThe Ohio State University     

New options for national population surveys: The implications of internet and smartphone coverage

Challenges to survey data collection have increased the costs of social research via face-to-face surveys so much that it may become extremely difficult for social scientists to continue using these methods. A key drawback to less expensive Internet-based alternatives is the threat of biased results from coverage errors in survey data. The rise of Internet-enabled smartphones presents an opportunity to re-examine the issue of Internet coverage for surveys and its implications for coverage bias. Two questions (on Internet access and smartphone ownership) were added to the National Survey of Family Growth (NSFG), a U.S. national probability survey of women and men age 15–44, using a continuous sample design. We examine 16 quarters (4 years) of data, from September 2012 to August 2016.Overall, we estimate that 82.9% of the target NSFG population has Internet access, and 81.6% has a smartphone. Combined, this means that about 90.7% of U.S. residents age 15–44 have Internet access, via either traditional devices or a smartphone. We find some evidence of compensatory coverage when looking at key race/ethnicity and age subgroups. For instance, while Black teens (15–18) have the lowest estimated rate of Internet access (81.9%) and the lowest rate of smartphone usage (72.6%), an estimated 88.0% of this subgroup has some form of Internet access.We also examine the socio-demographic correlates of Internet and smartphone coverage, separately and combined, as indicators of technology access in this population. In addition, we look at the effect of differential coverage on key estimates produced by the NSFG, related to fertility, family formation, and sexual activity. While this does not address nonresponse or measurement biases that may differ for alternative modes, our paper has implications for possible coverage biases that may arise when switching to a Web-based mode of data collection, either for follow-up surveys or to replace the main face-to-face data collection.     

A new extension of the FGM copula for negative association

In this paper we introduced a single parameter, absolutely continuous and radially symmetric bivariate extension of the Farlie-Gumbel-Morgenstern (FGM) family of copulas. Specifically, this extension measures the higher negative dependencies than most FGM extensions available in literature. Closed-form formulas for distribution, quantile, density, conditional distribution, regression, Spearman's rho, Kendall's tau, and Gini's gamma are obtained. In addition, a formula for random variate generations is presented in closed-form to facilitate simulation studies. We conduct both paired and multiple comparisons with Frank, Gaussian, and Plackett copulas to investigate the performance based on Vuong's test. Furthermore, the new copula is compared with Frank, Gaussian, and Plackett copulas using both Kolmogorov-Smirnov and Cramér-von Mises type test statistics. Finally, a bivariate dataset is analyzed to compare and illustrate the flexibility of the new copula for negative dependence.     

Exact Likelihood Inference for k Exponential Populations Under Joint Type-II Censoring

In this paper, when a jointly Type-II censored sample arising from k independent exponential populations is available, the conditional MLEs of the k exponential mean parameters are derived. The moment generating functions and the exact densities of these MLEs are obtained using which exact confidence intervals are developed for the parameters. Moreover, approximate confidence intervals based on the asymptotic normality of the MLEs and credible confidence regions from a Bayesian viewpoint are also discussed. An empirical comparison of the exact, approximate, bootstrap, and Bayesian intervals is also made in terms of coverage probabilities. Finally, an example is presented in order to illustrate all the methods of inference developed here.     

简单平均组合预测有效性的应用分析

通过实例分析,说明了当序列模式变动较大时,简单平均组合预测模型相对于其他组合预测模型的优越性,并且基于样本段的拟合精度不足以说明组合预测模型的外推预测精度。文中的分析对于组合预测模型的选择和应用具有实际参考价值。     

词义关系与英语写作

英语写作学习中,学习者写出的短文经常是词不达意,错误百出,缺乏生动与准确。究其原因,学习者词汇量有限,词义知之甚少是造成这些问题的主要障碍。但如果英语学习者能借助词义关系来扩大词汇量、正确掌握词义,他们驾驭词汇的能力必将提高,制约英语写作能力的词汇问题会迎刃而解,并使英语写作的表达更为生动与准确。     

结构一能动性干扰：问卷调查精度的局限性分析

以往对于问卷调查精度的探讨通常局限在“访问员“受访者”或“研究者”的三维关系当中,或专门针对问卷本身进行技术改良,很少注意到与这三者紧密相关的社会环境因素。以人为客体的社会领域研究不同于自然科学,势必会受到社会环境因素的干扰。而在问卷调查过程当中,影响调查精度最深的社会性因素是行政管理结构,这一结构性因素贯穿于问卷调查的始末,在这一结构作用下,行政管理者可以依附结构力量,能动地对问卷调查的结果产生影响,引导问卷结果偏向更加有利的一面,通过对以往研究过程当中所遇到的此类现象进行综合分析,总结出行政管理者所采用的四种能动性影响方式,从而探讨其对问卷调查的影响。最终,将这一影响问卷调查结果的现象称为“结构一能动性干扰”,并认为这一因素可能造成问卷结果在很大程度上会偏离真实,而对这一问题的解决,难以简单从以往三维关系或问卷技术改良上得到改善。