The purpose of this paper is to describe the characteristics of a model used for estimate the counterfactual effects of set aside policy in Italy. For this purpose it is used a regional model based on “positive” information contained in two different databases - FADN and IACSAGEA (an Italian administrative databank), and an evolution of PMP approach able to reproduce and properly simulate the entrepreneurial behaviour in each region. The paper clarifies in detail the procedure used in order to merge two different database and the main issue of the model useful for the proposed ex-post evaluation of relevant policy scenarios applied in agriculture.