Hello everyone,


I have an unbalanced panel data at subnational level based on survey years which differ from one country to another. In my analysis I have interactions terms between some variables which I need to center. Therefore, when centering these variables, it is correct to take out the mean of all values for all years from each value? Or it is necessary to compute the mean for all values, but for each different year.
Thanking you in advance.

Best wishes,
Stefan Bradeanu