摘要:

AbstractRecently BHATTI (1993) considered an efficient estimation of random coefficient model based on survey data. The main objective of this paper is to construct one sided test for testing equicorrelation coefficient in presence of random coefficients using optimal testing procedure. The test statistic is a ratio of quadratic forms in normal variables which is most powerful and point optimal invariant.

ISSN:0323-3847    

DOI:10.1002/bimj.4710370402

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractUsing sophisticated microscopy techniques, we observed the spatial pattern of bacteria colonizing a sterile 316L stainless steel coupon as bulk water containing bacteria flowed across the coupon. The experiments used stainless steel of differing roughness and surface chemistry. The ultimate goal was to identify surface features which influence bacterial adsorption. The immediate statistical goal was to distinguish patterns consistent with complete spatial randomness from patterns showing regularity or aggregation. This goal was accomplished by using modified analyses of distance functions commonly applied in field ecology. The method protected against a potential multiple comparisons problem. For the null value of the distance function, we calculated tolerance envelopes such that the tolerance level was simultaneous for all distances of concern. Computer simulation experiments showed that the nominal level was accurate. The methodology was effective for detecting and describing patterns of colonization known not to be completely spatially random.

ISSN:0323-3847    

DOI:10.1002/bimj.4710370403

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractMonte Carlo simulation of size and power of two proposed tests for linkage disequilibrium between two genes each with two alleles were investigated. Results were compared with two commonly used statistics, the correlation coefficientrand the log‐odds ratio tests. Depending on the sign of the linkage disequilibrium, the new tests were found to be more powerful than either of the correlation or log‐odds ratio tests. However, on average (positive and negative linkage disequilibrium) the Chi‐square test using the correlation coefficient was to a small extent more powerful than the other

ISSN:0323-3847    

DOI:10.1002/bimj.4710370404

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper is concerned with some versions of a stochastic model of aging proposed recently by TYURIN et al. (1993). In contrast to the commonly used Gompertz‐Makeham approach, the model yields a bounded hazard rate, thereby providing a better description of survival of old individuals in a population. Depending on plausible biological assumptions to be tested, only a few special cases of the basic model appear to be useful in experimental data analysis. We report the results of their application to experimental data on animal longevity obtained in a follow‐up study. When interpreted in terms of the model parameters, the data suggest drastically dissimilar patterns of aging for female versus male r

ISSN:0323-3847    

DOI:10.1002/bimj.4710370405

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractSelection studies involving multiple intercorrelated independent variables have employed multiple regression analysis as a means to estimate and partition natural and sexual selection's direct and indirect effects. These statistical models assume that independent variables are measured without error. Most would conclude that such is not the case in the field studies for which these methods are employed. We demonstrate that the distortion of estimates resulting from error variance is not trivial. When independent variables are intercorrelated, extreme distortions may occur. We propose to use Structural Equation Models (SEM), to estimate error variance and produce highly accurate coefficients for formulation of selection gradients. This method is particularly appropriate when the selection is viewed as happening at the level of the latent variables.

ISSN:0323-3847    

DOI:10.1002/bimj.4710370406

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractA Bayesian procedure is developed for the selection of concomitant variables in survival models. The variables are selected in a step‐up procedure according to the criterion of maximum expected likelihood, where the expectation is over the prior parameter space. Prior knowledge of the influence of these covariates on patient prognosis is incorporated into the analysis. The step‐up procedure is stopped when the Bayes factor in favor of omitting the variable selected in a particular step exceeds a specified value. The resulting model with the selected variables is fitted using Bayes estimates of the coefficients. This technique is applied to Hodgkin's disease data from a large Cooperative Clinical Trial Group and the results are compared to the results from the classical likelihood selection proced

ISSN:0323-3847    

DOI:10.1002/bimj.4710370407

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractLandmarks are used to summarize the shapes of ten haddock and nine whiting. Error variance models, after generalized Procrustes analysis, are compared using simulation tests. The power to discriminate between fish species is shown to be increased by permitting non‐affine transformations that correct for fish curvatur

ISSN:0323-3847    

DOI:10.1002/bimj.4710370408

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractA superpopulation model generates the probabilities of a Bernouilli random variable. The ranks of the involved variables are considered as survey weights. The distributionfeach linear rank statistic is derived under the null hypothesis for the two sample problem and for the casek2 when a simple random sampling or stratified sampling is used.The growth of a population of insects and the behavior of patients with imsomnia are studied using these procedures.

ISSN:0323-3847    

DOI:10.1002/bimj.4710370409

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0323-3847    

DOI:10.1002/bimj.4710370410

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0323-3847    

DOI:10.1002/bimj.4710370411

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY