We show in this study, an economist and a manager must be able to explain and predict economic trends and also understand the relationships that influence (production, consumption and distribution) that the business may suffer and could revive in the future. Linear regression was for us, a way that could give us a simple model to measure the impact of characteristics of a dependent variable on one or more well-defined variables; So an economic variable that explains the behavior of observed economic variables that influence the observed economic situation. If the economic situation does not allow admitting a linear regression model, we can transform the whole time in a linear model by appropriate methods and techniques. Hence it is easy to study the model as if it were a linear model in order to estimate the parameters to explain, understand and predict the future of the measured economic phenomenon. In this study, we use the experimental method which we analyze in four steps: - Definition of econometrics and some general notions of econometrics. - Definition of the model and to estimate the parameters. - Statement of assumptions and properties of the method used to estimate the parameters. - Make the judgment tests on the quality of the regression. And the technique is the method of ordinary least square to estimate model parameters.