5# sungmoo
运行是可以运行,可是为什么都是红叉?用上面链接那个数据(x2是我自己新建了一列):
. statsby _b ,by(id year): regress y x1 x2
(running regress on estimation sample)
command: regress y x1 x2
by: id year
Statsby groups
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但是by()里面只有一个变量ID时,就可以运行的。