各位大神,本人菜鸟,有个关于HLM的问题想向你请教一下:
以下是一个零模型的stata命令,分析个体层面和村庄层面的差异,现在想在里面加一个县级层面的聚类(cluster(county_id)),下面这种加法stata无法运行,麻烦大家帮我看看?万分感谢!
xtmixed sale || village_id: , cluster(county_id)
加入cluster(county_id)后stata报以下结果:
Performing EM optimization:
_xtm_mixed_ll_uu(): 3301 subscript invalid
_xtm_mixed_ll_u(): - function returned error
_xtm_em_iter_u(): - function returned error
_xtm_em_iter(): - function returned error
<istmt>: - function returned error