ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475640

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The process of determining the adequacy of the fitted model is referred to as testing for lack of fit. When replicate measurements are not available, there are several approaches to testing for lack of fit. This article presents some of these approaches on a continuum so as to provide a basis for a meaningful comparison. The issue of grouping data is also discussed. A usual approach of forming groups by arbitrary cutoffs in the space of predictor variables is questioned, and a data-splitting algorithm is recommended for separating groups.

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475641

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Relative and absolute risk models are often used in epidemiologic studies to describe the effect of exposure on age-specific mortality rates. Poisson regression analysis is used to obtain maximum likelihood estimates of unknown parameters and to assess goodness of fit of the models. It is common practice to base both estimation and the evaluation of goodness of fit on certain marginal totals. This approach is potentially misleading for relative risk models and is totally inappropriate for absolute risk models. To illustrate the situation, we present an example using data on smoking and lung cancer. In the example, the goodness-of-fit tests based on the marginal totals indicate that neither the absolute risk nor the relative risk model can be rejected, whereas the age-specific test statistics strongly reject both models. The validity of the marginal test is based on an assumption (i.e., of no exposure by age interaction) that is not satisfied in the example. We describe a more general approach to model evaluation that provides the analyst with summary information for various models of interest and provides guidance on how to identify good descriptive models.

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475642

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475643

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

It is well known that the ordinary least squares estimator ofXβin the general linear modelEy=Xβ, covy= σ2V, can be the best linear unbiased estimator even ifVis not a multiple of the identity matrix. This article presents, in a historical perspective, the development of the several conditions for the ordinary least squares estimator to be best linear unbiased. Various characterizations of these conditions, using generalized inverses and orthogonal projectors, along with several examples, are also given. In addition, a complete set of references is provided.

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475644

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475645

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475646

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475647

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Some statistical software refuses to perform regression and analysis of variance on data sets whose models allow no degrees of freedom for error variance. A related problem is getting statistical software to use a particular value for mean squared error for significance tests. We show how an external estimate of error variance can be entered via fake data in designed experiments so that the software works and the effects studied are not changed.

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475648

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This article describes a method for producing size-biased probability samples as originally proposed by Hanurav (1967) and Vijayan (1968). The complexity of the procedure has led to the development of microcomputer software that greatly facilitates the production of sampling plans as well as the computation of population estimates.

ISSN:0003-1305    

DOI:10.1080/00031305.1989.10475649

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor