Rivers Research Branch, National Water Research Institute, Canada Centre for Inland Waters, L7R 4A6, Burlington, Ontario, Canada.
Environ Monit Assess. 1989 Nov;13(2-3):295-304. doi: 10.1007/BF00394235.
In recent years, intensive biological monitoring studies have been carried out on the Niagara River by the Ontario Ministry of the Environment. The basic objective was to determine the relative bioavailability of trace contaminants at various locations in the river, and to identify sources. A recurring difficulty encountered with the generated data is that substantial portions of sample concentrations of many toxic pollutants are below the limits of detection established by analytical laboratories. Under the assumption that the distribution of the data is log normal, the likelihood ratio test for testing the equality of several means for type I censored data is derived and its use for evaluating the spatial variability of trace contaminants in the river is illustrated.
近年来，安大略省环境部在尼亚加拉河上进行了密集的生物监测研究。其基本目标是确定河流中不同位置痕量污染物的相对生物可利用性，并确定来源。生成的数据中经常遇到的一个困难是，许多有毒污染物的样本浓度很大一部分低于分析实验室确定的检测限。假设数据的分布是对数正态的，推导出了用于检验一类截尾数据中多个均值相等的似然比检验，并说明了其用于评估河流中痕量污染物空间变异性的用途。
