How to control an international but obmitted variable?

[Phuc Nguyen]

In my case, I deal with the firm-level data. I have a variable called X, which is an international index. I am using the standard two-way fixed effects regression. When controlling for year-fixed effects, of course, I faced the omitted variable problem (the X will be omitted when controlling for the years).

I am wondering how to solve this problem because I want to understand the predictability of the variable X on the dependent variable.

P/S: I am using the code reghdfe from STATA

[Carlo Lazzaro]

Phuc:
if -X- is time-invariant, there's no way that the -fe- estimatore can give you back a coefficient.

[Jared Greathouse]

You're not new here, I've seen you here long enough to know that someone's told you to present data and code first. Let's start there. Post your data (using dataex) and the result of the regression Stata gives you (also in code delimiters)