Figure 1
Test information function of the 19 items, with hip scores removed for hip patients and knee scores for knee patients. Its associated reliability level (r) and standard error of measurement (SEM) are included and Ï´ indicates the latent variable (standardized to a logit score of 0). Higher values of Ï´ indicate a higher number of painful joints. Logit values of -3, 0, and 3 correspond approximately to total comorbidity scores of 1, 9-10, and 18, respectively.