A reliability generalization study of the geriatric depression scale

Depression has proven to be a serious illness in older adults that often goes untreated because it is frequently misdiagnosed or is confused with other symptom patterns. One instrument that has been consistently cited in the literature as an effective indicator of depression in older adults is the Geriatric Depression Scale (GDS). The present study provided a reliability generalization (RG) study of the GDS in an effort to further distill psychometric properties of the scores generated by this measure. RG, a relatively new meta-analytic reliability procedure, was used to (a) identify the typical reliability of GDS scores across studies and (b) examine sources of measurement error across studies. Results from this investigation of 338 previously published research studies indicated that the average score reliability across studies was .8482 (SD =.0870) and that the number of items on the scale, scale SD, sample size, and participant population were the most important predictors of score reliability on this measure. Implications for the use of the GDS are offered.