The predictive influence function (PIF)in multivariate linear regres-sion is defined and the explicit expressions for PIF derived. Its properties are dealt with and a comparison of different influence measures made.

• 对多元线性回归模型定义了预测影响函数（PIF），导出了PIF的显式，研究了其性质，并对不同的影响函数进行了比较。