A wide range of material relating to the estimation of output gaps, including data, programmes and methods, are available at the dedicated CIRCA website.
The site is divided into three distinct sections.
The first section provides an overview of the production function methodology. It includes the NAWRU Kalman Filter program which has been developed by Christophe Planas and Alessandro Rossi of the European Commission's Joint Research Centre (Program GAP - Version 4.1, April 2009).
PROGRAM GAP is built for trend-cycle decompositions.It is currently used by DG ECFIN and Member States to decompose unemployment into its long and short-term components.
The second section of the website contains the detailed potential growth and output gap results from the latest Commission services forecasts as well as the underlying data sets and programs used in the calculations.
The third section, "Archives", contains the potential growth and output gap results from previous forecasting exercises.