Reactivity of polymyositis/scleroderma (PM/Scl) patients and controls in the PM1-α ELISA. Results obtained from three centers and based on 567 patients including PM/Scl patients (n = 40), Scl patients (n = 205) and PM patients (n = 40) as well as other controls were used to calculate comparative descriptive analysis. The diagram shows a significantly increased reactivity of the PM/Scl sera compared with the control groups. Comparative descriptives show vertical box-plots for each sample, side by side for comparison. The blue line series shows parametric statistics: diamond, mean and the requested confidence interval around the mean; notched line, requested parametric percentile range. The notched box and whiskers show non-parametric statistics: notched box, median, lower and upper quartiles, and confidence interval around the median; dotted line, connects the nearest observations within 1.5 interquartile ranges (IQR) of the lower and upper quartiles. + and ○, possible outliers – observations more than 1.5 IQR (near outliers) and more than 3.0 IQR (far outliers) from the quartiles. Vertical lines, requested nonparametric percentile range. SLE, systemic lupus erythematosus; HCV, hepatitis C virus; RA, rheumatoid arthritis.