请问在进行事件研究时,做到估计正常回报率时,这一步哪里错误啊?程序显示invalid syntax r(198);
gen predicted_return = . /*用于存放正常回报率*/
egen id_2 = group(id_1)
qui tabulate id_2
local N = r(r)
forvalues i=1(1) `N' {
qui reg net_ret rm1 if (id_2==`i' & event_window == 1)
predict p if id_2 == `i'
replace predicted_return = p if (id_2==`i' & event_window == 1)
drop p
}