if (!is.na(prediction[1]))
                                        {
                                                nb_jours = nb_jours + 1
-                                               error = error +
-                                                       mean((data$getCenteredSerie(cv_days[i]+1)[1:horizon] - prediction)^2)
+                                               error = error + mean((data$getSerie(cv_days[i]+1)[1:horizon] - prediction)^2)
                                        }
                                }
                                return (error / nb_jours)
 
                        prediction = rep(0, horizon)
                        for (i in seq_along(fdays))
-                               prediction = prediction + similarities[i] * data$getCenteredSerie(fdays[i]+1)[1:horizon]
+                               prediction = prediction + similarities[i] * data$getSerie(fdays[i]+1)[1:horizon]
 
                        if (final_call)
                        {
+                               prediction = prediction - mean(prediction) #predict centered serie (artificial...)
                                private$.params$weights <- similarities
                                private$.params$indices <- fdays
                                private$.params$window <-