进行stata系统广义矩阵回归时
. xtabond2 yingyu l.yingyu v8 v10 v34 v35 v36 v37 v38 v39 i.year, gmm(l.yingyu v8 v10) iv(i.year) robust
Favoring speed over space. To switch, type or click on mata: mata set matafavor space, perm.
No observations.
r(2000);
请问问题出现在哪里?求指教