今天刚开始练习使用stata,由于论文中实证部分需要进行wilconxon检验,将excel中的统计数据录入到了stata中。数据的基本格式是:有6列数据,分别为ROE1,ROE0,ROA2,每列数据下有58个样本。当我执行ranksum roe1,by(roe0)时,总是提示more than 2 groups found; only 2 allowed....请问如何处理,才能完成ranksum的检验??十分感谢。
ranksum tests the hypothesis that two independent samples (that is, unmatched data) are from populations with the same distribution by using the Wilcoxon rank-sum test, which is also known as the Mann-Whitney two-sample statistic (Wilcoxon 1945; Mann and Whitney 1947).
因为这个检验只适用于两个样本的情况。