At a regional level, research into cyclical analysis and the constmction of activity indexes with a periodicity inferior to the annual finds itself at a comparatively less developed stage than in neighbouring countries, given that hardly any sistematic contributions have been made in this field. This situation, aggravated by the lack of National Accounts of quarterly periodicity at a regional level has been the motivation for the present study, which sets out to improve and widen the existing instruments for short-term economic analysis at regional level in Spain. Briefly, the aim of the paper is to presenta methodology to develop monthly synthetic activity indicators which allow us to follow the cyclical evolution of a regional economy, with this methodology also being applicable at national level.

Keywords: factorial analysis, regional analysis, business cycle, economic indicators.