In almost all professional and scientific areas we are confronted daily with the need to extract quality information, from a set of observed data (salaries and administrations, voting intentions, annual sales, educational attainment and growth of a population, etc.), therefore is essential to have the knowledge for interpret and evaluate the results of statistical calculations. With this goal are studied some forms of data presentation and calculation of descriptive statistics measures. It makes a comparison between values of a variable in different registers in time and space and study the linear relationship between two variables. The last part is an introduction to the combinatorial calculation, calculation of probabilities and the concept of random variable in the discrete case.