Final multivariate linear regression analyses of FSS on sociodemographic, clinical and self-reported health status variables
| Variable | β | SE | t Value | p Value | Proportion of R2 explained uniquely | Proportion of R2 explained individually* |
| Intercept | 7.83 | 0.64 | 12.32 | <0.001 | ||
| Sex (male vs female) | −0.44 | 0.23 | −1.88 | 0.06 | 0.46% | 8.64% |
| SF-36 pain dimension | −0.02 | 0.006 | −3.21 | 0.001 | 1.34% | 36.38% |
| SF-36 mental health dimension | −0.04 | 0.006 | −7.13 | <0.001 | 6.59% | 29.67% |
| No of fibromyalgia tender points | 0.09 | 0.02 | 3.80 | <0.001 | 1.87% | 23.08% |
| HAQ | 1.07 | 0.25 | 4.24 | <0.001 | 2.33% | 37.79% |
| Methotrexate ever (yes vs no) | 0.59 | 0.22 | 2.66 | 0.008 | 0.92% | 7.28% |
| Residual standard error | 1.98 | |||||
| Residual degrees of freedom | 351 | |||||
| Multiple R2 | 54.51% | |||||
| Adjusted R2 | 53.73% | |||||
| Overall unique variation explained | 13.51% | |||||
| Overall shared variation explained | 41.00% | |||||
| Overall unexplained variation | 45.49% | |||||
| No of observations deleted due to missing data | 141 |
*The proportion of R2 explained individually differs from that in table 2 due to the deletion of 141 observations because of missing information. FSS, fatigue severity scale; HAQ, health assessment questionnaire; SF-36, medical outcome survey short form 36.