The EuroQol Instrument -- The descriptive system of the EuroQol Instrument -- The number of levels in the descriptive system -- First steps to assessing semantic equivalence of the EuroQol Instrument: Results of a questionnaire survey to members of the EuroQol Group -- Comparing general health related quality of life (HRQoL) questionnaires; EuroQol, Sickness Impact Profile and Rosser Index -- I…