Stata小白求助：输出边际效应图显示variable not found in list

Stata小白不知道这是出现了什么问题，检查了一下数据是连续的，不知道为什么出现variable Third not found in list of covariates的错误

*固定效应模型
xtreg GAP l.DIFI  Urban Gov Open Third Edu  i.year,fe r
gen DIFI_1 = L.DIFI
gen DIFI_1Urban = DIFI_1 * Urban
gen DIFI_1Third = DIFI_1 * Third
* 交互项
xtreg GAP DIFI_1 DIFI_1Urban Gov Open Third Edu i.year, fe
xtreg GAP DIFI_1 DIFI_1Third Urban Gov Open Edu i.year, fe
*边际效应
margins, dydx(DIFI_1) at(Urban=(0.2259(0.1)0.9768))
margins, dydx(DIFI_1) at(Third=(0.1675(0.1)0.7748))
marginsplot

你检查一下 Third变量是不是被omitted

我也遇到同样问题了，请问解决了吗？

可以参见https://www.statalist.org/forums ... -list-of-covariates。