In order to assess the explanatory power of previously calculated CIs, we used several panel data models. This approach allows us to compare the goodness of the CI with the disaggregated variables that compose it. The estimate considers three models, using: i) the CI constructed with the indicators that characterize each specific special economic area (CD_S), ii) the CI constructed with all the indicators (CI_T) and, iii) the last model considers the specific indicators as regressors (sI). Thus we expect, when CI is used as a single regressor, the associated coefficient results to be positive. This result would prove the goodness of this tool and the possibility of using it to demonstrate the validity of SEZs implementation rather than using a set of several indicators (Model 2; Model 4 -Table 3).