URL des Documents de travail : http://ces.univ-paris1.fr/cesdp/CESFramDP2010.htm A paraître dans Economics bulletinDocuments de travail du Centre d'Economie de la Sorbonne 2010.13 - ISSN : 1955-611XThe aim of this paper is to introduce a new methodology to forecast the monthly economic indicators used in the Gross Domestic Product (GDP) modelling in order to improve the forecasting accuracy. Our approach is based on multivariate k-nearest neighbors method and radial basis function method for which we provide new theoretical results. We apply these two methods to compute the quarter GDP on the Euro-zone, comparing our approach, with GDP obtained when we estimate the monthly indicators with a linear model, which is often used as a benchmark....