有负数怎么办？

看书上介绍方法：
1.Regression Diagnostics: An Introduction (Quantitative Applications in the Social Sciences) -  John Fox

2. Regression Diagnostics: Identifying Influential Data and Sources of Collinearity (Wiley Series in Probability and Statistics) 。David A. Belsley , Edwin Kuh , Roy E. Welsch

嗯，有负数就不行了~