Figure 1

Diagram of the factor analysis conducted to extract the global functional performance scale (oval on left) from primary rheumatology function tests measured on patients with rheumatoid arthritis. The three primary variables are represented by squares. The numbers next to arrows from the extracted to the primary variables are factor loadings. The numbers next to arrows from circles to primary variables represent uniqueness (U), the proportion of the variable that cannot be explained by the other primary scales.