标准差线 SD Line 标准差线通过平均点,它的斜率是当x的值增加一个x标准差,y的值增加一个y标准差 The SD line is a line that goes through the point of averages.And it’s slope is that it goes up by one SD of y every time . it goes over by one SD of x. the slope = SDySDx\frac{SDy}{SDx}SDxSDy​ 残差图