Hi all,

I'm a PhD student and greatly appreciate your valuable comments on the following.

I'm running a gravity equation for a panel with around 50,000 country pairs for 20 years. Also my equation includes lots of interaction variables (interact with year dummy) , that were used to convert time invariant variables in to time variant variables.

When I run the ppml command with country and time fixed effects, clustering the standard errors with country pairs, using strict option, I got the following;

Many warning messages saying most of the interaction variables has very large values, consider rescaling or recentering. Also, the 56 number of regressors were excluded to ensure that the estimates exist. Ultimately, after many iterations, the output was obtained without standard errors and p values.

My problem is Can I run the command without using Strict option?

Then I tried with ppml_panel_sg, I got the results with all the values. However, it took more than 10 hours to generate the estimation. Also, when I tried to the RESET test after the ppml_panel_sg estimation it runs forever without any output.

I also tried with ppmlhdfe. However, I got the error message r(3900) after a dayeven after I increase the mat size.


Your kind comments are greatly appreciated.

Niluka