Drawbacks to Integer Scoring for Ordered Categorical Data

Linear rank tests are widely used when testing for independence against stochastic order in a 2 x J contingency table with two treatments and J ordered outcome levels. For this purpose, numerical scores are assigned, possibly by default, to the J outcome levels. When the choice of scores is not apparent, integer (equally spaced) scores are often assigned. We show that this practice generally leads to unnecessarily conservative tests. The use of slightly perturbed scores will result in a less conservative and uniformly more powerful test.     

Estimates of a Treatment Effect Based on Censored Data Rank Tests

Linear rank test statistics are applied to the problem of estimating a treatment effect if two sets of censored failure time data are compared and the distributions of the log-failure times of the two samples are assumed to differ only in location. Rank tests for this accelerated failure time model are reviewed and Hodges-Lehmann type estimates for the shift parameter are proposed. Properties of these estimates are investigated, computational aspects are discussed and an example is presented.     

Linear Rank Statistics for the Simple Tree Alternatives

The problem of comparing several treatments with a control is considered. It is formulated as a test of homogeneity with one-sided alternatives that at least one treatment is better than the control, while no treatment is worse than the control. A class of linear rank tests for the simple tree alternatives is proposed, assuming a location model. The most efficient test of the proposed class for detecting a specified pattern is derived. Two optimal tests for use in the case of vaguely specified tree alternatives are derived. In a simulation study the power of these two tests are compared with the power of Kruskal-Wallis test. Recommendations about the use of the proposed tests are made.     

Rank Tests for correlated Random Variables

In this paper we consider the asymptotic distribution of linear rank-statistics allowing certain dependencies between the random variables. General theorems will be given, from which the results contained in SEN (1967a, 1967b, 1968), MEHRA /SEN (1969) and PURI /SEN (1971) can be derived. Applying these theorems we can derive ranktests for the two-sample problem for tied observations, for the two-factor mixed model with random interaction and for a hierarchical design. The distribution of the proposed teststatistics for small sample sizes is considered by Monte-Carlo studies.     

Sequential monitoring of randomization tests: stratified randomization

In many clinical trials, it is desirable to establish a sequential monitoring plan, whereby the test statistic is computed at an interim point or points in the trial and a decision is made whether to stop early due to evidence of treatment efficacy. In this article, we will set up a sequential monitoring plan for randomization-based inference under the permuted block design, stratified block design, and stratified urn design. We will also propose a definition of information fraction in these settings and discuss its calculation under these different designs.     

放线菌15个属中线型染色体和线型质粒的检测

在属于放线菌目 (Actinomycetales)链霉菌属 (Streptomyces)下的不同种中发现了约 5 0 0 0种抗生素和生理活性物质 ,其作用包括抗细菌、抗真菌、除草、杀虫、抗肿瘤和免疫抑制剂等[1 ] 。在属于放线菌目的红球菌属 (Rhodococcus)和诺卡氏菌属 (Nocardia)中有许多种可以降解多种工业有毒化合物 ,如苯酚、多卤联苯、脂环烃和硝基芳族等[2 ] 。一般细菌的染色体和质粒DNA为环型结构。近年来 ,人们利用脉冲电泳技术发现在链霉菌等少数细菌中存在线型结构的染色体和质粒[3] ,有的巨大线型质粒上还带有完整的抗生素生物合成基因簇[4 ]或降解多…     

On the Taxonomical State of Fritillaria sulcisquamosa and F. puqiensis

F. sulcisquamosa is slightly different from F. unibracteata in pollen morphology and differs external-morphologically from the latter in lacking trellised spots inside tepals. Therefore the former is reduced to a variety of the latter. F. puqiensis is found very similar to F. thunbergii both in pollen morphology and gross morphology. The former is different fromthe latter in geographical distribution and thus reduced to a variety of the latter.     

A Comparison of Algorithms for the Computation of the Mann-Whitney Test

An algorithm is proposed for the computation of the Mann-Whitney Test which only requires the separate ordering of the individual samples and is therefore more suitable than the usual one. It is also more suitable as to computation time than the algorithm described by KUMMER , 1981, if the two sample sizes are of the same magnitude.     

Formulas for the Computation of the WILCOXON Test and other Rank Statistics

A simple program for the computation of the WILCOXON test is introduced, which is suitable for implementation on a programmable desk computer. The allocation of ranks R_i is not necessary (see BERCHTOLD, 1979). In an analogous manner any ranks respectively rank sums also can be calculated, so that any test criterion or statistical estimate called rank statistic, may be completely constituted by computer programs without explicitely ranging of values.