DATA SF;

INFILE 'D:\MTDFREML_EG\G1_110522.prn' lrecl=120 MISSOVER;
INPUT ID $ 2-6 SIRE $ 10-14 DAM $ 18-22 S_LOC $ 32-33 D_LOC $ 48-49
BLOCK 60 REP 68-69 CAGE 75-77 DAY 84-85
LENGTH 90-93 HEIGHT 98-101 WIDTH 106-109 WEIGHT 114-117;

PROC PRINT; RUN;

PROC GLM DATA=SF;
CLASS SIRE DAM S_LOC D_LOC CAGE DAY;
MODEL LENGTH=SIRE DAM(SIRE) S_LOC D_LOC CAGE DAY ;
RUN;

分析结果：
Source DF Type I SS Mean Square F Value Pr > F
SIRE 16 825.2120458 51.5757529 474.34 <.0001
DAM(SIRE) 34 735.3824631 21.6288960 198.92 <.0001
S_LOC 0 0.0000000 . . .
D_LOC 0 0.0000000 . . .
CAGE 376 273.1517814 0.7264675 6.68 <.0001
DAY 0 0.0000000 . . .

为什么 S_LOC 和 D_LOC 这两个字符型变量没有统计结果呢？