At the beginning the second decade of the twenty-first century, between globalization, is fully confirmed that it is impossible to deny that the crisis, from which no country is safe, are inherent in the nature of the capitalist system and therefore, to be a source of greater systemic risk is essential to have alternative analysis tools and global character to make more accurate decisions. Considering these circumstances, it’s been demonstrated that the credibility of the economic policy, of a government, is subject to the perception of economic agents about the availability of international reserves by the Central bank, to cover his commitments in foreign currency. The above argument was quantified in an index of credibility of the economic policy of the Mexican Government which give citizens a rational and objective vision of the credibility, independent of the announcements of the government, to avoid that their decisions be disturbed.