摘要:

In this paper, the results of three simulation studies about discrimination are described. The first study investigates the use of James–Stein estimators in Fisher's discriminant function. The second compares the Anderson-Bahadur minimax linear discriminant function with the quadratic discriminant function and the last one deals with the choice of an unweighted between groups sum of squares and sum of products matrix instead if the usual between groups matrix

ISSN:0361-0918    

DOI:10.1080/03610919508813276

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

A confidence interval for the error variance following a preliminary test in the oneway random model is investigated. This interval is referred to as a pre-test confidence interval. The expected length of the pre-test confidence interval is shorter than that of the usual confidence interval. The coverage probability of the pre–test confidence interval is less than the nominal level. However, at some selected levels of significance, the coverage probability of the pre-test confidence interval is only slightly less than the nominal level but the maximum reduction in expected length is substantial

ISSN:0361-0918    

DOI:10.1080/03610919508813277

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

Tables of critical values are given, which can be used to execute interim analyses in clinical trials involving two groups when the joint distribution of the test statistics can be approximated by a multivariate normal distribution. Critical values are given for both the one and two interim analyses cases for a variety of partitions of α and correlation structures. Results of power calculations are presented, which reflect the effects of both the correlation structure and partitions of α.Several examples are given, which illustrate how to apply the tables to a variety of experiments

ISSN:0361-0918    

DOI:10.1080/03610919508813278

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

In consulting situations it is often difficult to select the most appropriate two-sample test for a particular situation. The objective of this research was to determine which two-sample test procedures were the most powerful when there were small differences in variability between the populations. A variety of skewed and symmetric distributions with unequal and equal variances were used in a Monte Carlo study to estimate the size and power of these tests. The tests maintained their size for the parameters used in this simulation. Those tests that were sensitive to location and scale shift alternatives were more powerful than the t-test and rank-sum test when there were small differences in variability between the groups

ISSN:0361-0918    

DOI:10.1080/03610919508813279

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

The aim of this study was to investigate the Type I error rate of hypothesis testing based on generalized estimating equations (GEE) for data characteristic of periodontal clinical trials. The data in these studies consist of a large number of binary responses from each subject and a small number of subjects (Haffajee et al. (1983), Goodson (1986), Jenkins et al. (1988)) Computer simulations were employed to investigate GEE based both on an empirical estimate of the variance-covariance matrix and a model-based estimate. Results from this investigation indicate that hypothesis testing based on GEE resulted in inappropriate Type I error rates when small samples are employed. Only an increase in the number of subjects to the point where it matched the number of observations per subject resulted in appropriate Type I error rates

ISSN:0361-0918    

DOI:10.1080/03610919508813280

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

Rao's Spacing Test is a useful and powerful statistic for testing uniformity with circular and periodic data. Previously published tables of critical values are incomplete, giving critical values only out to p=.l and n = 200. We extend those tables to n=1000 and for p-values from .001 out to 0.9. The extension will enable researchers to better evaluate the confidence with which they are accepting the null hypothesis, and to use the test with larger n

ISSN:0361-0918    

DOI:10.1080/03610919508813281

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

This note outlines a steepest descent approximation to the tail probability of the Neyman type A distribution.

ISSN:0361-0918    

DOI:10.1080/03610919508813282

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

Employing Bayesian finite population resampling techniques [referred to as finite population Bayesian bootstrap, FPBB, by Lo 1988], asymptotic posterior distributions of a linear combination of functions of stratum ratios and the corresponding confidence interval estimates are approximated. A straight forward algorithm is provided for the evaluation of the performance of the FPBB approximations to the asymptotic posterior distributions. Monte Carlo simulation is used to construct confidence interval estimates based on the FPBB method and to (graphically) demonstrate the performance of the FPBB method inapproximating the asymptotic posterior distributions of functions of ratios using Efron's (1982) Law School data. The results of the Monte Carlo investigations indicate that the FPBB based interval estimates compare favorably with the usual large-sample Bayesian interval estimates even for moderate bootstrap samples

ISSN:0361-0918    

DOI:10.1080/03610919508813283

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

Probability plots are popular and effective tools for the graphical assessment of the goodness–of–fit of a given dataset to a hypothesised probability distribution,Fsay, with densityf. The user can easily see any departures fromFthat there are, but the interpretation of such departures may not be immediately apparent. (It may take some time to work out their meaning, or else to resort to a set of rules for the interpretation of probability plots.) We investigate whether instant interpretability of these tools can be aided by a simple transformation which transfers visual assessment to the realms of familiar and immediate comparisons between densities. We seek to do sowithout smoothing, and see how far this allows us to go. The idea is very effective, and rather more so than quantile-quantile plots, forf's that have a single peak when the densitygfrom which the data truly come is also unimodal. The idea is much less appealing, however, whenfandghave different modalities from each other.

ISSN:0361-0918    

DOI:10.1080/03610919508813284

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor

摘要:

This paper proposes a mixed Poisson distribution which has a very long tail and also examines the full beta model of Kempton (Biometrika, 1975). The proposed distribution has a three-term probability recurrence relation that is stable in the backward direction, which is computationally desirable.The flexibility of the distribution to fit very long-tailed data is examined. The computation of probabilities is discussed and a numerical example is given.

ISSN:0361-0918    

DOI:10.1080/03610919508813285

出版商:Marcel Dekker, Inc.    

年代:1995

数据来源: Taylor