I am trying to recreate the results in this table. The results have been obtained by difference in difference estimation. I can obtain values from all columns except for column 5 and 6.
Column 5 says that it is obtained by subtracting column 1 from column 2, and this is simple to do for the means, however I don't know of a way to add OLS regression standard errors of 2 groups together to give a combined standard error, and I don't know of any other way to estimate the combined standard errors.
Does anyone know if/how this can be done. Or does anyone have any advice on alternative methods for obtaining these values.
Thank you for any help.