In addition , this paper choices indexes according to the correlation coefficient matrix and the actual meaning of the indexes . the method is simpler and more practicable . we compare our results with those in reference [ 8 ] and find that they are almost the same 本文在筛选变量时把相关系数矩阵和各指标的实际意义相结合,方法简单明了,所得结果与采用其他指标筛选方法所得结果基本相同。