摘要:

The term 'principal points' originated in a problem of determining 'typical' heads for the design of protection masks, as described by Flury. Two principal points in the mask example correspond to a small and a large size. Principal points are cluster means for theoretical distributions, and sample cluster means from a k -means algorithm are non-parametric estimators of principal points. This paper demonstrates that maximum likelihood estimators and semi-parametric estimators based on symmetry constraints typically perform much better than the k -means estimators. Asymptotic results on the efficiency of these estimators of two principal points for four symmetric univariate distributions are given. Simulation results are provided to examine the performance of the estimators for finite sample sizes. Finally, the different estimators of two principal points are compared using the head dimension data for the design of protection masks.

ISSN:0266-4763    

DOI:10.1080/02664769723503

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

This paper is a review of the use of contextual information in statistical image analysis. After defining what we mean by 'context', we describe the Bayesian approach to high-level image analysis using deformable templates. We describe important aspects of work on character recognition and syntactic pattern recognition; in particular, aspects of the work which are relevant to scene understanding. We conclude with a review of some work on knowledge-based systems which use context to aid object recognition.

ISSN:0266-4763    

DOI:10.1080/02664769723512

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

In this paper, we present a further modification of Endres's method to construct the problem of minimizing the average fraction inspected (AFI) for the continuous sampling plan CSP-1 under inspection error. The measures of average outgoing quality under perfect and imperfect replacement conditions are considered. The formulae for searching the smallest clearance number i for minimizing the AFI for a CSP-1 plan are also provided. The solution procedure of the proposed method is more reliable, clearer and easier than that of Endres.

ISSN:0266-4763    

DOI:10.1080/02664769723521

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

In regression analysis, a best subset of regressors is usually selected by minimizing Mallows's C statistic or some other equivalent criterion, such as the Akaike lambda information criterion or cross-validation. It is known that the resulting procedure suffers from a lack of consistency that can lead to a model with too many variables. For this reason, corrections have been proposed that yield consistent procedures. The object of this paper is to show that these corrected criteria, although asymptotically consistent, are usually too conservative for finite sample sizes. The paper also proposes a new correction of Mallows's statistic that yields better results. A simulation study is conducted that shows that the proposed criterion performs well in a variety of situations.

ISSN:0266-4763    

DOI:10.1080/02664769723530

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A procedure to choose the best non-parametric estimator from among all nonparametric methods to fit regression curves is described. The methodology that is proposed prevents a lack of fit at the edges of the regression curve. The method is summed up in a few steps to facilitate its application by researchers. The procedure is applied to the determination of various curves that explain the anti-inflammatory activity of diverse extracts of Sideritis foetens and phenylbutazone against the time elapsed from the application of the agent which provokes the inflammation. Discussion shows that it is possible to obtain valid conclusions about the effects of the different products and to establish comparisons between them. Such conclusions are not possible when starting from the classical statistics methods usually employed in pharmacology.

ISSN:0266-4763    

DOI:10.1080/02664769723549

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The aim of this paper is to undertake the problem of adapting some multivariate statistical methods (MANOVA, cluster analysis with simultaneous test procedures T 2 based on Roy's union-intersection rule and canonical variate analysis) max and describing their possible usage in the evaluation and interpretation of the phenotypic diversity with regard to quantitative traits in cereal collections. The presented procedures are used in a case where experimental data have been obtained from single-replicated trials conducted at the same location over a few years. In such cases, data can be nonorthogonal connected accessions x years cross-classification with none or one observation in a given subclass. The application of the suggested procedures is illustrated by a numerical example of a winter rye collection from the Plant Breeding and Acclimatization Institute in Radzikow near Warsaw (Poland).

ISSN:0266-4763    

DOI:10.1080/02664769723558

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We investigate the use of the chi-square control chart as a simple multivariate method for shopfloor monitoring of compositional process data. Although this chart is usually considered to be applicable only with multinomial process data, we show that it is also valid, in a certain asymptotic sense, for compositional data that arise from the Dirichlet distribution. For general compositional data, we show that the chi-square statistic can be used for process monitoring, provided that we make a simple adjustment to the degrees of freedom in the chi-square reference distribution. This method is illustrated and compared in four examples with the T 2 chart based on log-ratio transformation of the data.

ISSN:0266-4763    

DOI:10.1080/02664769723567

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Non-parametric tests that deal with two samples include scores tests (such as the Wilcoxon rank sum test, normal scores test, logistic scores test, Cauchy scores test, etc.) and Fisher's randomization test. Because the non-parametric tests generally require a large amount of computational work, there are few studies on small-sample properties, although asymptotic properties with regard to various aspects were studied in the past. In this paper, the non-parametric tests are compared with the t -test through Monte Carlo experiments. Also, we consider testing structural changes as an application in economics.

ISSN:0266-4763    

DOI:10.1080/02664769723576

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor