数据请见附件。用SAS做固定月份效应是这么做吗？
step two 之后，直接做 step four 会报错。提示要保证每个月份里每个股票只能有一个观测值，查 sas support 说可以用
平均值替代多个观测值的方法来做，这样就必须用 step three 来做。


请熟悉这个问题的大侠指教。谢谢！


** Step one;
PROC SORT DATA = panal out =a;
BY month stock; RUN;

** Step two:delete observations that contains missing variables;
data b;set a;nmiss=cmiss(of informedbuy -- ret);if nmiss = 0;run;

** Step three :In order to use PROC PANEL, you need to aggregate the data so that you have unique timevalues within each cross section.
One possible way to do this is to run a PROC MEANS on the input data set and compute the mean of all the variables by stock and month,
and then use the output data set ;
proc means data = bnoprint;
where Relationship ^= "本人";
by month stock;
var informedbuy -- ret;
output out=b(drop= _type__freq_) mean= n=/autoname;
run;

** Step four: fixed month effect regression;
PROC TSCSREG DATA = aoutest=result noprint;
stockmonthstock;
modelret =dummy log_size bm r_1y/FIXone;
RUN;
quit;