早在1954年,Ahrens就发现岩石、矿物样本中微量金属元素的浓度分布与常量元素不同。它不呈正态分布而呈对数正态分布。而Vistelius认为大多数微量元素的浓度分布呈大的正偏。由于算术平均值和标准差只适用于表达正态分布样本。因而,用算术平均值表示样本的集中性、用算术标准差表示样本的 As early as 1954, Ahrens discovered rocks. The concentration distribution of trace metal elements in mineral samples is different from the constant elements. It is not normally distributed but lognormally distributed. Vistelius believes that the concentration distribution of most trace elements is largely positive. Since arithmetic mean and standard deviation apply only to expressing normal distribution samples. Thus, the arithmetic mean means the sample’s concentration, and the arithmetic standard deviation means the sample’s