摘要:

Although it is generally felt that the all-subsets, or “best” subset, approach is better than forward selection and backward elimination, the sequential procedures are still widely used. To see what advantage there is in doing all-subsets, this paper gtves both theoretical and empirical comparisons. It is shown that the difference in favor of all-subsets can be arbitrarily large in examples where there are predictors which do poorly alone but do very well together. Also. empirical comparisons on nine data sets show big dilrerences favoring all-subsets, when the differences are measured on the data (sample values). However, fairer comparisons based on known population values show very small differences favoring all-subsets. The only exception is the one data set which has predictors which do well together but poorly alone.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489609

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Derivative-free nonlinear least squares algorithms which make efficient use of function evaluations are important for fitting models defined by systems of nonlinear differential equations. A new Gauss-Newton-like algorithm with these properties is developed. The performance of the new algorithm (called Dud for “doesn't use derivatives”) is evaluated on a number of standard test problems from the literature. On these problems Dud competes favorably with even the best derivative-based algorithms.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489610

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

We review existing methods of experimental design for discriminating between rival regression models. Box and Hill's algorithm and its extensions. and the work of Atkinson and Fedorov and Atkinson and Cox are particularly considered. The relationship between the various methods is pointed out. Several unrelated and less formal algorithms are also mentioned. The need for a multipurpose design strategy, which takes into account the need to design for estimation of the parameters of the correct model, is stressed.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489611

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Computational methods are derived which permit the construction of confidence regions and intervals for location and scale parameters in a specified family of continuous distributions. The methods, which follow the procedures proposed by Barr and Davidson [1] and Easterling [2], are based on the Kolmogorov-Smirnov goodness of fit statistic, and are readily adapted to type II censored samples.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489612

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Formulas and tables of significance points are presented for the distribution of the one sample Kolmogorov-Smirnov statistics for truncated or censored samples as proposed by Barr and Davidson [1]. Approximate formulas for the significance points are given for sample sizes exceeding 25; they are based on the asymptotic distribution derived by Koziol and Byar [2]. In addition, it is shown how the exact power of these tests for finite sample sizes can be calculated.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489613

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A modification is given for theWE, statistic for testing that a sample comes from the exponential distribution. The modification is for the case where the origin is known, and has been devised to make use of the tables already provided by Shapiro and Wilk. Power studies are given to show that it is worthwhile using the modification when possible.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489614

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Tolerance limits and confidence limits on reliability, which closely approximate exact limits. are proposed for the two-parameter exponential distribution. These approximations have the advantage that solutions to both the tolerance limit problem and the confidence limit problem can be written explicitly.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489615

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Some problems of inference and prediction arise when the Weibull process is used to model reliability growth. Their solution can be based on certain functions involving the maximum likelihood estimators. Integral expressions for the distributions of these functions are presented which make it possible to compute, using numerical integration, the probabilities needed for inference.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489616

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The biplot graphical display of matrices is proposed as a data analytic tool for diagnosing the type of model to fit the data. Rows and columns of the data matrix are represented by markers—the diagnosis proceeds by examining these markers for collinearity. Thus, for example. if setIof row markers are collinear and a set J of column markers are also collinear. a Tukey degree-of-freedom-for-non-additivity is diagnosed for the submatrix of these I-rows andJ-columns: if the two lines are at 90°. an additive model is diagnosed. Mandel type models are similarly diagnosed when either the row or the column markers are collinear but not both.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489617

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Previous work by Gentleman and Wilk on outliers in two-way tables is summarized, and their statisticQKis discussed. Instead of a plot ofQKvalues, we propose a two-stage test for the presence of two outliers or one outlier. Percentage points for the test statistics are estimated by Monte Carlo generations, and approximations to the percentage points are suggested. The 8 × 12 case is examined in detail and extensions to other cases are briefly discussed.

ISSN:0040-1706    

DOI:10.1080/00401706.1978.10489618

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor