ISSN:0192-2521    

DOI:10.1002/em.2860070802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0192-2521    

DOI:10.1002/em.2860070803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractCytogenetic analysis has been used for several years in attempts to detect the mutagenic effects of suspect agents. Yet there remain many questions related to statistical analysis. While several procedures have been and are being used, many unfortunately are not always appropriate for the types of data actually obtained. Two general analysis approaches are discussed together with ways to insure that the test assumptions are reasonably met. Because assay sensitivity is a major concern, the sample size issue is discussed with examples for specific situations.

ISSN:0192-2521    

DOI:10.1002/em.2860070804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA Monte‐Carlo simulation is performed to evaluate the power of the Terpstra–Jonckheere test for monotonic trend as applied to binary data. The effects of the magnitude and shape of the underlying response and of varying the number of treatment levels for in vivo experiments in cytogenetics are examined. It is shown that choice of the number and spacing of the treatment levels can be critical factors in determining the power of the test. These findings indicate that selection of the proper experimental design is a very important step in the process of conducting a viable st

ISSN:0192-2521    

DOI:10.1002/em.2860070805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractAlgorithms for tests of homogeneity and trend with medians are presented. Under certain conditions the tests are more efficient than many standard nonparametric tests on one‐way classification designs. Computationally the tests are very simple and could be performed by hand or with the help of a calculator. Application to certain types of data derived in cytogenetics is pointed out with an exampl

ISSN:0192-2521    

DOI:10.1002/em.2860070806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractDirect mutagenicity tests offer the opportunity of monitoring human populations to detect evidence of genetic damage that occurs in vivo. As such these tests offer the potential of linking earlier exposures to mutagenic agents to subsequent health effects. One such test detects mutant T‐lymphocytes that arise in vivo in human peripheral blood. Statistical analysis of the value observed, the variant frequency (Vf), is the subject of this paper. We present and illustrate procedures for finding confidence intervals for a single variant frequency and for the ratio of two independent variant frequencies. We also derive formulae for required sample size to ensure adequate power to detect a specified change in a single variant frequency or a specified difference between two variant frequencies. Our approach is to exploit the approximate normality of the natural logarithm of a Poisson distributed variable. The procedures developed appear to be quite accurate even for the small (5–15) values often observed in the variant frequency assay. Moreover, the procedures are very easy to use and should prove valuable to investigators involved in direct mutagenicity test

ISSN:0192-2521    

DOI:10.1002/em.2860070807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA number of parametric models are evaluated for the analysis of data arising from in vivo cytogenetics studies. Parallels between the structure of data arising from these studies and teratology studies are discussed. Evaluation of historical control data demonstrates the importance of recognizing non‐independence of responses among cells within an animal. Models investigated that take into account this non‐independence of responses include the beta‐binomial, negative binomial, and correlated binomial models. Results indicate that the beta‐binomial model performs best in terms of its ability to fit available control data. Suggestions for the incorporation of historical control data, based upon the two‐stage structure of the candidate models,

ISSN:0192-2521    

DOI:10.1002/em.2860070808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractData from 1,111 controls from assays run over 11 years are examined to determine a most powerful statistical procedure for detecting a mutagenic effect. It is concluded that the data do not show a constant probability of chromosomal abnormalities and that the data do not fit a simple Poisson or binomial distribution. Empirical Bayes techniques are used to derive a test that declares an effect if three or more cells in a group of 50 tested contain abnormalities.

ISSN:0192-2521    

DOI:10.1002/em.2860070809

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractPublished evidence for human sex and race differences in sister chromatid exchange (SCE) levels is reexamined. There is substantial support for the conclusion that women average approximately 0.5 SCE/cell higher than men among normal healthy adults. An index of heterogeneity for SCE counts for cells from a single subject is introduced, and this statistic is applied to the data of Butler [1981]. who compared Caucasians, Blacks, Native Americans, and Orientals with regard to SCE levels. There is evidence in Butler's data of differences in the heterogeneity index among these four racial groups, but this finding needs independent verification in a larger study.

ISSN:0192-2521    

DOI:10.1002/em.2860070810

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA list of readily available computer programs for analysis of different types of experimental data is compiled. Some of these programs have been tested by the author for accuracy, and yet several others need to be checked by the users against existing tables and documents. The errors, to the author's knowledge, have been pointed out. Many of these programs may be used as subroutines in analyzing data derived from experiments in cytogenetics as well as other fields.

ISSN:0192-2521    

DOI:10.1002/em.2860070811

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY