sas如何按变量分类求平均值

***对Sashelp.Class数据集中,按性别对年龄求均值.并输出到A数据集,平均值变量名 为Age_Mean;
Proc Summary Data=Sashelp.Class Nway;
Class Sex;
Var Age;
Output Out=A(Drop=_:) Mean=Age_Mean;
Run;
Proc Print;
Run;
确定不是同一个人?