Application of public-domain statistical analysis software for evaluation and comparison of comet assay data
Application of public-domain statistical analysis software for evaluation and comparison of comet assay data
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DOI：
10.1016/j.mrgentox.2006.01.002
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发表时间：
2006-04-30
影响因子：
1.9
通讯作者：
Monserrat, JM
中科院分区：
文献类型：
--
作者：
Verde, PE;Geracitano, LA;Monserrat, JM
利用公共领域的统计软件R系统，提出了一种新的角分析数据统计分析方法(即：尾矩)。分析策略考虑到彗星化验数据的分布。像尾矩一样，通常是偏态的，不服从正态分布。用来模拟彗星分析数据的概率分布包括：威布尔分布、指数分布、Logistic分布、正态分布、对数正态分布和对数-Logistic分布。在这种方法中，还认为实验单位之间观察到的异质性是彗星分析数据的一个随机特征。该统计模型可以用位置参数m(Ij)、尺度参数r和实验单位之间的变异性参数0来表征。在对数标度中，参数mij附加地依赖于治疗和随机效应，如下所示：log(m(Ij))=a(0)+a(1)x(Ij)+b(I)，其中exp(a(0))近似代表对照组的平均值，exp(a(1))可被解释为相对于对照组的相对损害风险，x(Ij)是试验组的指标，而exp((Bi))是假设服从均值为1和方差为0的伽玛分布的个体风险效应。型号选择是基于Akaike的信息标准(AIC)。实际数据来自于对比目鱼血液样本的彗星分析，以及从河口多毛目Laeonereis actita的细胞悬浮液样本。这一统计方法表明，彗星化验数据应在考虑到这些测量的重要特征的建模框架下进行分析。模型的选择和实验单元之间的异质性在这些数据的分析中起着核心作用。(C)2006爱思唯尔B.V.保留所有权利。
A novel approach for statistical analysis of cornet assay data (i.e.: tail moment) is proposed, employing public-domain statistical software, the R system. The analytical strategy takes into account that the disuribution of comet assay data. like the tail moment, is usually skewed and do not follow a normal distribution. Probability distributions used to model comet assay data included: the Weibull, the exponential, the logistic, the normal, the log normal and log-logistic distribution. In this approach it was also considered that heterogeneity observed among experimental units is a random feature of the comet assay data. This statistical model can be characterized with a location parameter m(ij), a scale parameter r and a between experimental units variability parameter 0. In the logarithmic scale, the parameter mij depends additively on treatment and random effects, as follows:log(m(ij)) = a(0) + a(1)x(ij) + b(i),where exp(a(0)) represents approximately the mean value of the control group, exp(a(1)) can be interpreted as the relative risk of damage with respect to the control group, x(ij) is an indicator of experimental group and exp((bi)) is the individual risk effects assume to follows a Gamma distribution with mean 1 and variance 0. Model selection is based on Akaike's information criteria (AIC). Real data coining from comet analysis of blood samples taken from the flounder Paralichtys orbigriyanus (Teleostei: Paralichtyidae) and from samples of cells suspension obtained from the estuarine polychaeta Laeonereis actita (Nereididae) were employed. This statistical approach showed that the comet assay data should be analyzed under a modeling framework that take into account the important features of these measurements. Model selection and heterogeneity between experimental units play central points in the analysis of these data. (c) 2006 Elsevier B.V. All rights reserved.