... an unsatisfactory(depending on group size and number of items) Cron-bach's alpha value (i.e. α below a value of 0.7 to 0.6), thefactor analysis was repeated, restricting it to two or threedomains. ... specific measurement of health-related quality of life ina clinical trial of respiratory rehabilitation. J Clin Epidemiol1999, 52:187-192.15. Bruil J: Development of a quality of life instrument ... moduleoriginally consisted of 8 domains (Limitations, Symp-toms, Worry, Allergy, Sleep, Medical, Interpersonal andLack of energy) with a total of 32 items. Analysis of themodule as described...