The mean value of any parameter and its changes are usually discussed, when ecotoxicological studies are carried out. However, also the variation of any parameter and its changes can be important components of the responses to environmental contamination. Although the homogeneity of variances is commonly tested, testing is done for the use of correct statistical methods, not because of exploring the possibility that variability and its changes could be important components of environmental responses. We evaluated recent aquatic toxicological literature and found that in the majority of articles indicating that homogeneity of variances was tested and giving the result of testing, the assumption of homogeneity was not fulfilled. Further, it was observed that in some studies experimental treatment clearly affected the variability. In this commentary we discuss the reasons for variability: measurement errors, experimental design, genetic heterogeneity and phenotypic plasticity, and conclude that even after accounting for experimental design and genetic makeup significant variability remains. This plasticity may change in environmental responses as suggested by a hypothetical example, and as confirmed by experimental data. As a consequence, the changes of variability can be significant, even when the means do not differ. Because of this, variability and its changes should always be analysed and reported. This will be easy, since the datasets are exactly the same for comparing the variances and means, and as normally variances are tested for homogeneity. It is likely that much new information about the responses of organisms to environmental contamination will be obtained. However, the present journal practises tend to discourage one from concentrating on anything but the mean. In contrast, we think it is imperative that variability is always included as an endpoint in data analysis in the future.

在进行生态毒理学研究时，通常会讨论任何参数的平均值及其变化。但是，任何参数的变化及其变化也可能是对环境污染做出反应的重要组成部分。尽管通常测试方差的均一性，但要使用正确的统计方法进行测试，而不是因为探索了可变性及其变化可能是环境响应的重要组成部分的可能性。我们评估了最近的水生毒理学文献，发现在大多数文章中表明检验了方差的均一性并给出了测试结果，未满足均质性的假设。此外，据观察，在某些研究中，实验处理明显影响了变异性。在这篇评论中，我们讨论了变异的原因：测量误差，实验设计，遗传异质性和表型可塑性，并得出结论，即使考虑了实验设计和遗传构成，仍然存在显着的变异性。如一个假设的例子所暗示的那样，并且如实验数据所证实的，这种可塑性可能会改变环境响应。结果，即使均值没有差异，可变性的变化也可能是显着的。因此，应始终对可变性及其变化进行分析和报告。这将很容易，因为用于比较方差和均值的数据集完全相同，并且通常会测试方差的同质性。很有可能会获得有关生物对环境污染的反应的许多新信息。但是，目前的期刊实践往往会阻止人们只专注于中庸之道。相反，我们认为在将来数据分析中必须始终将可变性作为终点来考虑。