Identifying and Interpreting Convergence Clusters Across Europe
The authors examine the spatial and temporal distribution of per capita income across Europe. The analysis is based on a cluster methodology which allows for an endogenous selection of regional clusters using a multivariate test for stationarity where the number and composition of clusters are determined by the application of pairwise tests of regional contrasts.
Link
http://www.econ.cam.ac.uk/dae/repec/cam/pdf/cwpe0414.pdf