原来以为只有Pearson Correlation. 今天学到对不同类别的变量，应做不同类型的相关处理。

Variable Y\X	Quantitiative X	Ordinal X	Nominal X
Quantitative Y	Pearson r	Biserial rb	Point Biserial rpb
Ordinal Y	Biserial rb	Spearman rho/Tetrachoric rtet	Rank Biserial rrb
Nominal Y	Point Biserial rpb	Rank Bisereal rrb	Phi, L, C, Lambda

需要搞清楚的细节还很多。
参考：
https://www.andrews.edu/~calkins/math/edrm611/edrm13.htm
https://en.wikipedia.org/wiki/Phi_coefficient
http://web.pdx.edu/~newsomj/pa551/lectur15.htm