频数表，处理缺失类别

data new;
set old end =eof;
...;
run;
run;

*with by;
data new;
set old; by bygroup;
count =1;
output;
...weight count; ...; run;

if you want sas to recognize what you have added, you have to use weight variable in proc freq. since weight =0 is allowed in freq. jingju

我觉得我明白你的意思呵呵
proc format;/*首先要根据你的完整格式定义一个format*/
value level
3="高"
2="中"
1="低"
;
run;
data xx;
format level level.;/*把value给format一下*/
sn=1001;level=3;
output;
sn=1002;level=3;
output;
sn=1003;level=3;
output;
sn=1004;level=2;
output;
sn=1005;level=3;
output;
run;
proc summary data=xx completeTypes;
class level/PRELOADFMT ;/*这两关键词是必须的*/
output out=aa;
run;

最后输出的结果就是:

低  0
中  1
高  4

同时proc means过程也能用这个关键词
不过proc freq不能用
不过没关系 可以用proc summary 代替