一、独立性检验的基本思想独立性检验的基本思想类似于数学中的反证法.其目的是为了确认“两个分类变量有关系”这一结论成立的可信程度.它首先假设结论不成立,即“两个分类变量没有关系”成立,在该假设下,构造的随机变量K~2的值应该很小.如果由观测数据计算得到的K~2的观测值很大,则在一定程度上说明假设不合理.因此可以根据随机变量K~2的含义来确定该假 First, the basic idea of ​​independence test The basic idea of ​​independence test is similar to the anti-card law in mathematics.The purpose is to confirm the credibility of the conclusion that “the relationship between two classification variables ” It first assumes that the conclusion does not hold , That is, “there is no relationship between the two categorical variables ”. Under this assumption, the value of the random variable K ~ 2 should be small. If the K ~ 2 value calculated from the observed data is very large, To a certain extent, it shows that the hypothesis is unreasonable, so the false can be determined according to the meaning of random variable K ~ 2