•说法一:
procsql;• createtable m13 as
• selectavg(csp)as avglev,
• count(stock) asnobs,
• ind,year
• from m12 groupby ind,year;•quit;
••说法二:
•/*计算各行业的观测值数目em.regtj*/
•create table em.regtjas select distinct ind,year,
•n(stkcd)as nn
•from em.idxgroup by ind,year;