including interactive instruments in ivreghdfe - estimates post: matrix has missing values

[Owen Hoy]

Hi Guys,

I am using ivreghdfe to compute a fixed effects iv regression and I am getting the error: estimates post: matrix has missing values.

 ivreghdfe employed (lnbirth=nonrep7173 nonrep7173#c.distance nonrep7475 nonrep7679) ib1.st#c.yearsq unemp inc rape [aweight=pop], absorb(st year) first

The issue only occurs when I insert the interaction between nonrep7173 and distance as an instrument. I have also tried explicitly creating the interaction term and the same error occurs. For reference, nonrep7173 is a dummy variable taking either 0 or 1 as values, and distance is a continuous variable taking values between 0 and 1.

I am not sure why including this variable creates an error. Does anyone have any thoughts?

Kind regards,
Owen.

[Owen Hoy]

In addition, the error doesn't occur when rep7173, the interaction AND distance itself is included i.e. including

nonrep7173##c.distance

However, I only want:

nonrep7173 nonrep7173#c.distance

Without distance as a covariate.

Regards,
Owen.