Hey,
I am trying to analyse trade dynamics between different countries using gravity equation model. The model uses ppml estimator with 2 dummy trade as dependent variable and 2 dummy variables, exporter and importer time fixed effects, and pair wise fixed effects as independent variables. While running the estimation stata excludes two of the regressors to ensure that the estimate exist. What can be the possible reason for such exclusion ? Also I need the estimated values of regressors to calculate a new variable, now since there is a break in the continuation of the series, is it possible to create a new variable using a single command to account which excludes the two values omitted by stata and includes all the other values.
I have attached the screenshot of the error for your convenience.
Thank you.
I am trying to analyse trade dynamics between different countries using gravity equation model. The model uses ppml estimator with 2 dummy trade as dependent variable and 2 dummy variables, exporter and importer time fixed effects, and pair wise fixed effects as independent variables. While running the estimation stata excludes two of the regressors to ensure that the estimate exist. What can be the possible reason for such exclusion ? Also I need the estimated values of regressors to calculate a new variable, now since there is a break in the continuation of the series, is it possible to create a new variable using a single command to account which excludes the two values omitted by stata and includes all the other values.
I have attached the screenshot of the error for your convenience.
Thank you.
