Reliability
Reflecting the manner in which the GDS was constructed, numerous studies show high internal consistency. Yesavage et al. reported an alpha coefficient of 0.94 in a mixed sample of unaffected and depressed elderly people (N = 100) (1, p43). Agrell and Dehlin found an alpha of 0.90 in 40 stroke patients (12, p1192) whereas Lyons et al. tested 69 hip fracture patients and reported alpha coefficients of 0.88 at admission and 0.93 at discharge (13, p205).Rule et al. obtained an alpha coefficient of 0.82 and a split-half reliability of 0.80 for 193 university students, higher than the figure for Zung’s Self-Rating Depression Scale (SDS) (14, Table 1). In a further study of 389 community residents, Cronbach’s alpha ranged from 0.80 to 0.85 across five age groups of 29- to 99-year-olds