二、标准差 1.求取标准差的一般公式 利用算术平均数作为样品的代表,进行统计分析,是目前分类学中探索变异规律时经常采用的最基本的方法之一。优点是算法简便;在相同的环境条件下受取样的影响较小;加上平均数本身是直接由样品内各个变量求得的,因此具有普遍的代表性。如果分析用的样品内部各变量之间的差异不大,那未用平均数来反映群体(即总体)的特征就比较合适。然而,单靠平均数有时是不够的,这是因为平均数虽 2. Standard Deviation 1. General Formula for Standard Deviation The use of arithmetic mean as a representative of a sample for statistical analysis is one of the most frequently used methods in the current taxonomy to explore the law of variation. The advantage is that the algorithm is simple; it is less affected by the sampling under the same environmental conditions; and the average itself is directly derived from the various variables in the sample and is therefore generally representative. If there is not much difference between the variables within the sample for analysis, it is more appropriate not to use the average to reflect the population (ie population) characteristics. However, the average alone sometimes is not enough, because of the average