| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Internal consistency of the SF-12 component summary scores is generally high (Cronbach’s >0.82 and 0.75, for SF-12 PCS scale and MCS scale, respectively. |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
Test–retest reliability of the SF-12 administered 2 weeks apart is adequate: r = 0.89 for PCS and r = 0.76 for MCS. |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
For both the PCS and MCS scales, changes in scores between test and retest averaged less than 1 point, and at the second administration, 85% scored within the 95% confidence interval (95% CI) of the score at the first administration. |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
The SF-12 was developed using regression analysis methods to select and score 12 items from the SF-36 to reproduce the PCS and MCS scales in the general US population. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Tested |
| Brief Description |
The 2-factor conceptual structure of the SF-12 (PCS and MCS) has been confirmed in several population-based and clinical studies. |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
The SF-12 PCS and MCS scores correlate 0.95 and 0.96 with the SF-36 PCS and MCS scores, respectively. These findings have been replicated in the general populations of 9 European countries (Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, and the UK), with very high correlations between SF-12 PCS and SF-36 PCS scores (r = 0.94–0.96) and SF-12 MCS and SF-36 MCS scores (r = 0.94–0.97). Clinical trials data from patients with osteoarthritis and rheumatoid arthritis also indicate good criterion validity of the SF-12 in rheumatology, with strong correlations between the SF-12 and SF-36 PCS scores and the SF-12 and SF-36 MCS scores (r = 0.92–0.96). |