Massachusetts Audubon Society, 159 Main Street, 01930, Gloucester, MA, USA.
Environ Monit Assess. 1987 Mar;8(2):163-80. doi: 10.1007/BF00403111.
Eleven similarity measures were used to assess the impacts of clam digging on the infauna of one intertidal mud-flat. When the similarity matrices were clustered using a divisive polythetic algorithm two different conclusions were possible from the dendograms produced. Dendograms generated by 3 coefficients indicated digging had an impact on areas dug more than once, while the 8 others did not. In addition, existing data from an impact analysis of a power plant effluent were re-analyzed using 5 different coefficients. In this case, three of the five coefficients gave results which indicated that the benthic community at the effluent pipe was different from that present at the control. Two coefficients gave the opposite conclusion - the populations were not different.These results indicate that the objectivity of cluster analysis, as it has come to be used in impact studies, is only apparent, not real. Too many subjective choices are made in selecting algorithms and methods of interpretation. Objective criteria need to be developed for the choices made, based on the intrinsic and ecological properties of the quantitative methods. Some criteria that have been developed are discussed, and used to determine which coefficients are best suited for the two data sets analyzed. To reduce the number of subjective choices made an analysis of variance of the similarity matrix is presented as an alternative to clustering.
11 种相似性度量被用于评估采蛤对一个潮间带泥滩底栖动物的影响。当使用分裂多标准算法对相似性矩阵进行聚类时，从产生的谱系图中可能得出两种不同的结论。由 3 个系数生成的谱系图表明，采挖对多次采挖的区域有影响，而其他 8 个系数则没有。此外，利用 5 个不同的系数对发电厂废水影响的分析数据进行了重新分析。在这种情况下，5 个系数中的 3 个给出的结果表明，废水排放管处的底栖生物群落与对照点的不同。两个系数给出了相反的结论——种群没有差异。这些结果表明，聚类分析的客观性，就像它在影响研究中被应用的那样，只是表面上的，而不是真实的。在选择算法和解释方法时，做出了太多的主观选择。需要根据定量方法的内在和生态特性，为所做的选择制定客观标准。讨论了一些已经制定的标准，并用于确定哪些系数最适合分析的两个数据集。为了减少主观选择的数量，提出了对相似性矩阵的方差分析作为聚类的替代方法。
