The present article aims to identify and present in an initial phase some features of the evalua-tion used in the field of public policies such as: the impact evaluation, the cost-benefit evaluation, ex-ante evaluation, post-hoc evaluation, etc. On the other hand, this analysis aims to identify which matemathical statistics methods and techniques can be activated in order to correlate the field of the operational research of the public administration, of the public policies with the types of the evaluation previously identified in order to respect the principle of the internal validity and of the external validity to reach valid results.