摘要:

The exact distribution of the Gini's rank association coefficient G under absence of association is given for samples of size up to 15. It was previously known for samples of size up to 10. The accuracy of some approximate distributions proposed in the literature is then evaluated

ISSN:0361-0918    

DOI:10.1080/03610919308813105

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor

摘要:

A random-effects model of the relationship of drug dosage to potentially correlated binary variables for efficacy andtoxicity is developed, in which values of logistic dose-response parameters are allowed to vary among individuals. Parameter estimation is difficult, but Monte Carlo simulations can be used to determine the consequences of incorrectly applying a fixed-effects model of independence of efficacy and toxicity to data actually generated by the random-effects mechanism. Of particular interest is the spread of individuals' therapeutic windows' of doses about the overall population window that would be deduced from application of the model of independence. The scatter and dimensions of the windows are strongly influenced by the variances of the median effective (μ1) and median toxic (μ2) doses and by their separation (μ2− μ1)- The correlation between μ1and μ2has surprisingly little effect on the pattern of individuals' windows, but it does result in an imbalance in the values of μ1 in subjects with and without intolerable side effects. That imbalance, however, translates into only small differences in parameter estimates obtained with and without censoring of efficacy measurements for subjects experiencing toxicity, at least for the parameter values used in these simulations

ISSN:0361-0918    

DOI:10.1080/03610919308813106

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor

摘要:

Process capability indices CPU,CPL,and Cpk have been used to measure the capability of a process. Tests on determining thecapability of a process are presented.Critical values are given in order to determine whether a process is capable.For a given sample size and a given significance level,the power of each test is considered.Tables for critical values andpower values are also presented

ISSN:0361-0918    

DOI:10.1080/03610919308813107

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor

摘要:

Partial correlations can be used to statistically control for the effects of unwanted variables.Perhaps the most frequently used test of a partial correlation is the parametric F test,which requires normality of the joint distribution of observations.The possibility that this assumption may not be met in practice suggests a need for procedures that do not require normality.Unfortunately,the statistical literature provides little guidance for choosing other tests when the normalityassumption is not satisfied.Several nonparametric tests of partial correlations are investigated using a computer simulation study.Recommendations are made for selecting certain tests under particular conditions

ISSN:0361-0918    

DOI:10.1080/03610919308813108

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor

摘要:

A simulation study was performed to examine the relative efficiency of thirteen estimators against OLSE across thirty combinations of orientation, variance and known parameter vector, encompassing several different degrees of collinearity. Estimation procedures include principal components, ridge and generalized ridge, jackknife, shrinkage and fractional principalcomponent methods. Overall, in the face of collinearity the biased estimators perform better than OLSE, but no 'optimal' estimator emerges, and a suitable choice of estimator will depend on the circumstances

ISSN:0361-0918    

DOI:10.1080/03610919308813109

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor

摘要:

The time-dependent Poisson process with the intensity function A (t) = eα+βtwas considered by Cox and Lewis (1966) systematically,where they discussed the statistical test of the hypothesis β= 0. In this paper, the estimation and the hypothesis testing problems of the population parameters are considered. Especially we focus on the exact-hite properties of the maximum likelihood estimator (MLE) of β.

ISSN:0361-0918    

DOI:10.1080/03610919308813110

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor

ISSN:0361-0918    

DOI:10.1080/03610919308813094

出版商:Marcel Dekker, Inc.    

年代:1993

数据来源: Taylor