Figure 1
From: The determination and measurement of functional disability in rheumatoid arthritis
A partial causal model of disease activity and outcome in rheumatoid arthritis. Rectangles represent observed variables, and ovals and rounded rectangles represent latent (unobserved) variables. ESR/CRP, erythrocyte sedimentation rate/C-reactive protein; HAQ, Health Assessment Questionnaire; SF-36, Medical Outcomes Study Short Form 36; QOL, quality of life; JT, joint.