负超几何随机变量期望与方差的一种简捷计算

摘要

给出了负超几何分布的概率模型,通过将负超几何分布随机变量进行和式分解,比较简捷地计算了它的期望和方差,并指出文献[4]计算的期望和方差是错误的.%We give the probability models of negative hypergeometric distribution at first, and second we give a shortcut method for caculating its expectation and variance using the decomposition theorem of a negative hypergeometric random variable. At last we point out that the literature [4-] to calculate the expectation and variance are wrong.