| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Cronbach’s was 0.94 and split-half reliability was 0.94. Recent review of internal consistencies measured by multiple studies using both oral and written administrations with various populations reported Cronbach’s ranging from 0.69 – 0.99 for the long form; short form internal consistency has been reported at 0.74 – 0.86. |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
Correlations (r 0.84 – 0.85) at 1–2 weeks retest suggested the GDS scores (both short and long forms) reflect stable individual differences. |
| C. Reliability interobserver or Measurement error | Not Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
|
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Final test items for both forms selected via empirical item selection from items based on characteristics of depression in the elderly |
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description | |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
High correlations have been noted between the GDS and other depressive symptom measures. The GDS more consistently differentiates depressed from nondepressed seniors than other depression measures. The GDS short form is highly correlated with the original long form |