Luciano JV, Barrada JR, Aguado J, Osma J, García-Campayo J. Bifactor analysis and construct validity of the HADS: a cross-sectional and longitudinal study in fibromyalgia patients. Psychological Assessment. 2014 Jun;26(2):395-406.
See CW, Srinivasan M, Saravanan S, Oldenburg CE, Esterberg EJ, Ray KJ, Glaser TS, Tu EY, Zegans ME, McLeod SD, Acharya NR, Lietman TM. Prior elicitation and Bayesian analysis of the Steroids for Corneal Ulcers Trial. Ophthalmic Epidemiol. 2012 Dec;19(6):407-13.