This paper analyses the impact of the PCT data on the European Patent Office (EPO) patent statistics, and explores methods to improve the timeliness of the EPO indicators by estimating the number of PCT applications which enter the EPO regional phase.
Link
http://www.olis.oecd.org/olis/2005doc.nsf/43bb6130e5e86e5fc12569fa005d004c/6b0dc1e6f11e1b93c1256fa3004a2a30/$FILE/JT00178247.PDF