人们往往在获得某些子集的统计特征参数的同时,欲得到全集的同一统计量的统计特征参数。如,某地层单元由 K 种岩性组成,各岩性中采有足够的岩样,分析其中 Cu 元素的含量。按岩性分别统计计算各岩性样品 Cu 含量的平均值、标准离差、样品数(参与统计计算的),然后,再去统计计算整个地层单元中 Cu 元素的平均含量、标准离差、总样品数、变异系数等 People often get the statistical characteristic parameters of some subsets while obtaining the statistical characteristic parameters of the same set of statistics. For example, a stratigraphic unit is composed of K kinds of lithology. There are enough rock samples in each lithology, and the content of Cu element is analyzed. Calculate the average Cu content, standard deviation and sample number (involved in statistical calculation) of each lithology sample by lithology, then calculate the average content of Cu element, standard deviation, total deviation Sample number, coefficient of variation and so on