proc reg data=jiliang.white2;
model demand=price promotion advertisement grade;
weight w;
run;

跟
data jiliang.white2;
set jiliang.white2;
demandw=demand*w;
pricew=price*w;
promotionw=promotion*w;
advertisementw=advertisement*w;
gradew=grade*w;
run;
proc reg data=jiliang.white2;
model demandw=pricew promotionw advertisementw gradew w/noint;
run;
运行的结果为什么不一样啊？？？急。。。。