下载了一个论文的数据去运行，下面代码的最后一行报错，好像是gmm的命令，但是又跟我搜的不一样
use E:\dataverse_files\all_hexagon_iv.dta, clear
keep if year == 1910
gen merge_var = 10000*city_cd + hexagonID
sort merge_var
merge 1:1 merge_var using E:\dataverse_files\estimation_sample_merged.dta
drop _merge
gen cutoff1 = 10000
gen cutoff2 = 10000
gen const = 1
xi i.city_cd
x_gmm x_meters y_meters cutoff1 cutoff2 whitediff10 const _Icity_cd_2-_Icity_cd_11 blackdiff10 const _Icity_cd_2-_Icity_cd_11 IV_black10 , xreg(12) inst(12) coord(2)
command x_gmm is unrecognized
去掉了x_gmm前面的x_更是不行
求i大家指教