摘要:

Sometimes, the normal maintenance data recorded by repair shops, working around systems as small as cars or as large as factories, can be used to perform reliability evaluations both in terms of distribution of times to first failure and in terms of expected number of failure in a given time interval. Some examples fiom the field show the use of two estimation procedures proposed for parts and systems respectively, in the context of Non-stationary Stochastic Process. Every attempt has been made to make the whole work practice-oriented, as well as in relation to dimensioning and managing the repair shops themselves.

ISSN:0266-4763    

DOI:10.1080/02664768900000038

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

Citrus Tristeza Virus (CTV) causes a most destructive citrus disease in many parts of the world. The strategy for controlling the disease in Israel is based on the eradication of virus-infected trees, detected by an immunological method. A model for the spread and control of CTV is described. The disease spread depends on an infection rate parameter and on a detection coefficient. Both parameters vary with time. Simulation of the model under different conditions assists us to make decisions regarding the control of CTV disease.

ISSN:0266-4763    

DOI:10.1080/02664768900000039

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

There is a great deal of interest in studying the joint action between chemotherapeutic agents, particularly in screening compounds for therapeutic synergism. In this paper, we propose an approach to study therapeutic synergism using logit models when the data are binary. The key is to convert the definition of therapeutic synergism to its equivalence in terms of the model parameters. Thereby, evaluating therapeutic synergism amounts to examining parameter estimates in the most parsimonious model fit to the data. The proposed approach was further applied to an experimental situation where it was desirable to rank several test articles when administered jointly with a common compound in the treatment of shock.

ISSN:0266-4763    

DOI:10.1080/02664768900000040

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

In this study attempts were made to fit several statistical distributions to the surface maximum, minimum and mean daily wind speed records at 24 Kenyan sites. The statistical distributions fitted included the 2 and 3 parameter Lognormal, Pearson type III, Log Pearson type III, the 2 and 3 parameter Weibull distributions. The various parameters for these distributions were obtained from the methods of moments and maximum likelihood. The goodness of fit of the various distributions were investigated at each of the 24 sites using the Kolmogorov-Smirnov and x2 tests. The corresponding standard errors were also computed.

ISSN:0266-4763    

DOI:10.1080/02664768900000041

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

When the elements of a design matrix are rational numbers and the variances of the observations are rational multiples of a common real constant, the covariances being zero, the design matrix may be factorised into a product of matrices which have usefil statistical interpretations. The main factor matrices have integer elements, while the other factor matrices are diagonal with rational elements. Weights which are rational numbers, and missing observations, are readily accommodated. A computer is usually needed to find the factors. This paper shows how, once the factors have been found, they may be employed for any suitable set of observations without further need for such assistance.

ISSN:0266-4763    

DOI:10.1080/02664768900000042

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

The logic underlying the formulation of statistical tests of hypothesis can be counterintuitive for the non-mathematician, e.g. to test whether two treatments are different, why suppose they are equal? When introducing the topic of hypothesis testing, it is easy to present the formal fiamework for the testing procedure without explaining the logic behind it. In courses for statisticians, one may often (unjustifiably) rely on the understanding of probability concepts as a foundation for understanding statistical inference, but in courses taught to non-statisticians where there is minimal discussion of probability, it is essential that explanations must be based on concepts the students can readily understand. The method proposed here for teaching the concept of hypothesis testing makes an analogy to the judicial system, whereby a person is assumed innocent until sufficient evidence warrants a verdict of guilty. Analogies for the different elements of statistical tests are presented and discussed, together with a classroom fiamework for discussion of statistical tests.

ISSN:0266-4763    

DOI:10.1080/02664768900000043

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

The estimation of the land equivalent ratios is proposed to be done by the (sum of) ratios of means of intercrop yield to sole crop yield. The bias and standard error of the estimates are obtained for large samples. Comparisons of the cropping systems have been made on the basis of these estimates and illustrated with field data.

ISSN:0266-4763    

DOI:10.1080/02664768900000044

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

A variety of statistical problems lead to the estimation of parameters in a linear model or solving a system of linear equations. The problem of estimating linear parameters can be solved by adopting well known matrix inversion techniques. In this paper a mathematical algorithm has been developed for inverting a special class of matrices.

ISSN:0266-4763    

DOI:10.1080/02664768900000045

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

In this paper, the logistic regression model is applied to analyse some prison data. Precisely the model is used to predict the future conduct of a discharged prisoner. The consequence of this is that on the basis of the predicted probability of ‘success' one can say whether or not it is beneficial to retain a convict in prison for a long period of time.

ISSN:0266-4763    

DOI:10.1080/02664768900000046

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor

摘要:

Mardia (1980) proposed a bi-directional test of spatial independence based upon the sample variogram which has a X2-distribution under the null hypothesis. We give here a modified test whichleads to improvement to the X2-distribution approximation to the size. We introduce some other tests including a four-directional extension, and analogous tests based on the sample correlation coefficient. Their power is compared with the modified bi-directional test for a doubly geometric alternative, and this limited power study indicates that the modified bi-directional test is more powerful.

ISSN:0266-4763    

DOI:10.1080/02664768900000047

出版商:Carfax Publishing Company    

年代:1989

数据来源: Taylor