statsby _b _se r2=e(r2) n=e(df_r),clear by(code): reg rif rmf rbf hm   
foreach v of var _b*{
loc s=substr("`v'",4,.)
g _t_`s'=`v'/_se_`s'
g _p_`s'=ttail(_eq2_n, abs(_t_`s'))*2
}