In this work, an analysis of the external factors that determine the importance of predictive variables within the day-ahead electricity market has been carried out. These analyses are then considered to establish the degree of influence of the variables under study over the price of the market. Each predictor of the model is estimated taking into account its nature and associated information using Multiple Linear Regression and least squares methods. The competitive results obtained show the importance of the analysis of the variables correlations and posterior selection of characteristics afforded as a previous step to the inclusion of the predictors in the corresponding model. Keywords: electricity price, daily market, variables, demand, production, prediction