[Veeckman Art]

Dear Carlo,

Thank you for your response, however I do not fully understand what you wrote, and thus what I should do.
Do you mean that I should add the different regions separately in the model too, and not only as the interaction term for CEP?
(add only, South, East and West Europe, since North Europe is my reference category)

Kind regards

[Carlo Lazzaro]

And should I add the the sum of CEP and interaction effect of Eastern Europe to calculate the total effect of CEP on CFP for European regions...

My concern was simply about your plan to rule out conditional main effects and interactions about South and West Europe from your calculation and focus on Eastern Europe only.
I also fail to understand what does this calculation add to the information already provided by the regression model: I would have find more methodologically correct to compare the coefficient concerning the differen European regions (but I'm not familiar with the data you're dealing with, though).
Obviously, you should consider that all the coefficients you got are adjusted for the remaining predictors (put differently, there's no such a thing as a "pure" effect on regressand of a given predictor whenever you deal with a multiple regression).