输入的命令是:xthreg2 RDrate_w $control , rx(x4_w) qx(market) thnum(1) trim(0.01) bs(300 ) grid(300)
报错:
There exist time-invariant individual(s) (maybe only one obs): RDrate_w ROA_w Lev_w hefin_w s
> ize_w x4_w
<istmt>: 3499 thestm2() not found
自变量是研发投入强度,因变量是财政补贴,控制变量是ROA、资本积累率、资产负债率、前十大股东持股比例、企业规模
请问是哪里有错误?