https://blog.csdn.net/cherrylvlei/article/details/81430447?utm_medium=distribute.pc_relevant.none-task-blog-2~default~baidujs_baidulandingword~default-0-81430447-blog-77859173.235^v43^pc_blog_bottom_relevance_base1&spm=1001.2101.3001.4242.1&utm_relevant_index=3
为什么样本方差计算是除以n-1
https://blog.csdn.net/Hearthougan/article/details/77859173
这篇也可以参考