LB Mokkink*, CB Terwee, DL Knol, PW Stratford, J Alonso, DL Patrick, LM Bouter and HCW de Vet
* Corresponding author: LB Mokkink w.mokkink@vumc.nl
BMC Medical Research Methodology 2006, 6:2 doi:10.1186/1471-2288-6-2