摘要:

AbstractThis paper discusses the basic types of dynamical behavior of populations obtained in discrete models, such as monotonous dynamics, stable limited cycles, and chaotic variations. All these modes are shown to have possibly arisen in the evolution of limited populations under the effect of density‐independent selection. This effect together with that of density‐dependent non‐selective factors has been termedF‐selection, which is characterized by independence of relative fitnesses from population density, whereas populations may be ecologically limited; in other words, absolute fitnesses prove to be a function of population size. The characteristic ofF‐selection is to be not sensitive to changes in population size but to lead to fluctuations, that create conditions for achieving density‐dependen

ISSN:0323-3847    

DOI:10.1002/bimj.4710240602

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractUsing a quantitative genetic model, this paper compares four different methods for estimating genetic variance components. Given various genetic parameters, data were generated and estimates computed. The number of negative estimates, the sample mean, the sample variance, and the sample mean squared error were computed for each method. It is shown that, if the genetic values are not very small, the traditional MATHER‐JINKSmethod is at least as good as any other method. The ML method might be preferable only if the genetic values are very small and the number of loci larg

ISSN:0323-3847    

DOI:10.1002/bimj.4710240603

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractLet {Xn, n≧1} be a sequence of independent and identically distributed random variables. Supposen(K)=minnfor whichXn>Xk, withKfixed andn>K. We will characterize the exponential distribution by considering the distributional properties ofXkandXkandXn(k

ISSN:0323-3847    

DOI:10.1002/bimj.4710240604

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractFor the case of the LEHMANNalternatives the paper presents some new facts on the MANN‐WHITNEYstatistic and, in particular, its varianceV(p, m, n), wherep = P(xi

ISSN:0323-3847    

DOI:10.1002/bimj.4710240605

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractNew ascertainment models taking into account partitioning by sex and without any constraint concerning dominance of alleles are proposed. These originate beginning from two major pathways. The first pathway assumes independence and that the family sizes for both males and females are known. The second pathway assumes dependence and that only the total family size is known. Ascertainment probabilities based on several different types of dependence are found. Results are obtained for incomplete multiple ascertainment.

ISSN:0323-3847    

DOI:10.1002/bimj.4710240606

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe complexities of long‐term tumorigenicity assays are discussed and statistical approaches suggested. Account must be taken of how tumors are discovered, and a reasonable distinction might be made between self‐evidencing tumors (palpable tumors and rapidly lethal tumors) and those identified only on necropsy. Tumor autolysis can pose difficulties. The nature of the experimental design must be taken into account‐the study can be completely randomized, or may involve litter‐matching, or circumstances may require that all members of a litter be treated alike. The use of a logrank procedure or a closely equivalent Mantel‐Haenszel procedure can provide a unifying approach, but modification needs to be made so as to take into account‐data on non‐self‐evidencing tumors. Censoring plays a role, whether because of eventual study termination or because losses to competing risks are treated as censored observations. Where there are several non‐zero dosage levels, the analysis can be modified according to the dosage metric used. Multiplicity of statistical tests can arise whether because a number of questions are asked or because a multiplicity of tumor sites have to be considered. Some of the kinds of questions raised have been addressed in earlier papers by various of the present authors, to which the reader is referred. Specifically new material is given on use of the jackknife so as to take into account that the unit of observation is the litter or even the group of litters caged together. Various problems were found to attend the application of the jackknife i

ISSN:0323-3847    

DOI:10.1002/bimj.4710240607

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA heuristic three‐step procedure for analysing multidimensional contingency tables is given to meet the requirements of a mixed analysis from both hypotheses‐ruled and data‐ruled type. The first‐step provides the structure of relationships among the attributes by fitting an appropriate unsaturated log‐linear model to the data of the given contingency table. Restriction to elementary hierarchical models allows to get them by combining pairs of conditional independence. The result of the first step may be regarded as a certain validisation of real model ideas. In the second step the significant pairs of conditional dependence are analysed in regard to the levels of the condition complex. Only such significant pairs are to be considered, in general, where the condition complex does not include the response variable. The third‐step may test special subtests in that significant two‐dimensional tables found in step two or may extend the general statements by partitioning, the corresponding test statistics in additive components. Application examples demonstrate the general l

ISSN:0323-3847    

DOI:10.1002/bimj.4710240608

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractBy a simple example it is shown how in special cases the variable kernel estimate may not give the correct qualitative impression of the estimated density.To exclude such effects a slightly modified definition of the bandwidth of the kernels is proposed.

ISSN:0323-3847    

DOI:10.1002/bimj.4710240609

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractWe investigate the efficiencies of TIKU'S(1967, 1980) modified maximum likelihood (MML) estimators of location and scale parameters of symmetric distributions and show that they are remarkably efficient (jointly). We develop test statistics (based on MML estimators), analogous to the classical tests based on sample means and variances, for testing the equality of two means (the population variances not necessarily equal). We show that these tests are remarkably robust to distributional assumptions and generally more powerful than the well‐known nonparametric tests (WILCOXON, normal‐score, KOLMOGOROV‐SMIRNOV). We generalize the results to testing linear contrasts of means in experimental design (the error variances not necessarily equal). We show that the analogous tests based on ‘adaptive’ robust estimators (wave, bisquare, HAMPEL,) etc., GROSS(1976, and other ‘adaptive’ robust estimators) give misleading

ISSN:0323-3847    

DOI:10.1002/bimj.4710240610

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

ISSN:0323-3847    

DOI:10.1002/bimj.4710240601

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY