Today’s citizen lives more and more immersed in indices and graphics that not only give him daily information, but also allow him to make timely decisions with measurable accuracy levels. The same could happen, for example, to a private business manager or a public administrator or to a researcher on people’s tastes and ways of thinking. Getting a hinge of human beings habits and behaviors requires the previous achievement of a series of research projects with a strict and suitable use of statistical techniques. We describe some of the cautions that should be taken into account when using Statistics in opinion polls, to assure the results validity.