摘要:

Linear logistic or probit regression can be closely approximated by an unweighted least squares analysis of the regression linear in the conditional probabilities provided that these probabilities for success and failure are not too extreme. It is shown how this restriction on the probabilities translates into a restriction on the range of the coefficient of determinationR2so that, as a consequence,R2is not suitable to judge the effectiveness of linear regressions with binary responses even if an important relation is present.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475836

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Graphical methods for testing goodness of fit are reviewed and classified as transformations of P-P and Q-Q plots. Survival and cumulative hazard plots for censored data, probability plots, and generalized residual plots are included. Difficulties in interpretations arise when the points are grouped more closely together in particular areas of the plot. This problem commonly occurs in cumulative hazard and Q-Q plots, especially in large data sets, but can occur in P-P plots when censoring is present. An empirical rescaling of the axes is proposed to overcome this problem. The techniques are applied to reliability and clinical trial data sets.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475837

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Kaplan–Meier graphs of survival and other timed events are an extremely effective way to summarize outcome data from some types of clinical studies, but information on dates and the interaction among events is lost. A new mode for presenting such data is proposed, an Eventchart, that aids in looking at the study as a whole by simultaneously displaying the timing of 2–3 different types of events, including censoring and time-dependent covariate events. The chart helps to monitor accrual and can be used to “guesstimate” the amount of information resulting from additional enrollment and/or follow-up. Eventcharts are designed to supplement, not replace, quantitative methods of analysis or conventional survival graphs. Data from bone marrow transplantation and AIDS studies are used to illustrate the method. Terminology is suggested for describing the concepts and distinguishing among the complex of events studied in modern clinical trials, including timed events, loss and date censoring, and time-braided events.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475838

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In the two-sample means test, the need for a preliminary variance test and the special emphasis given to the equal variance assumption are questioned. The conclusions can be easily used in the classroom to teach the two sample means test.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475839

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Link and others have derived formulas for the moments of certain discrete probability distributions using various finite-difference operators. In this article, we establish a method of obtaining moments of certain discrete distributions that makes use of differential operators. The derivations are elegant and more compact than derivations using standard methods. Students in a first-year mathematical statistics course are typically more acquainted with differential operators than with difference operators. Contrasted with difference operators, this familiarity affords a better opportunity to introduce the connection between operator mathematics and probability in such courses. However, we propose that both operators be employed: differential operators to introduce the connection and difference operators to broaden the students' exposure and prepare them for such courses as time series analysis.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475840

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This article considers a class of multivariate (dependent) variables that includes those that are obtained as scale mixtures of elliptically symmetric distributions. We provide a simple, intuitive proof that the ratio of two such variables has a general Cauchy distribution. This result extends the results of DeSilva concerning properties of a certain class of dependent multivariate symmetric stable distributions.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475841

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The delta method is an intuitive technique for approximating the moments of functions of random variables. This note reviews the delta method and conditions under which delta-method approximate moments are accurate.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475842

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This article shows that two slightly differential exponential families are needed for commonly used linear models. The first family is the usual textbook definition. The second family, due to a lemma by Gautschi, is needed for some cross-classified variance component models.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475843

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In textbooks on multivariate statistics, the topic of multivariate analysis of variance (MANOVA) is usually presented in terms of the decomposition of the “total sums of squares and products” matrix into the “within” and “between” matrices, often called the “hypothesis” and the “error” matrices. While this decomposition can be justified by maximum likelihood estimation and hypothesis testing under normality assumptions, better motivation is provided by a finite mixture model in which no assumptions beyond the existence of second moments are needed. We propose that the decomposition be interpreted in terms of estimates of conditional and unconditional moments, rather than as just an algebraic identity.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475844

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Hands-on exercises have proven themselves to be excellent vehicles for communicating and reinforcing the concepts taught in process improvement, introductory statistics, and design of experiments courses. This is especially true as related to the planning aspects of data collection and designed experiments. In this article, some hands-on process improvement exercises developed and used by Rohm and Haas statisticians in industrial short courses are reviewed. All exercises can be conducted using readily available materials with times ranging from 20 minutes to four hours.

ISSN:0003-1305    

DOI:10.1080/00031305.1992.10475845

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor