Boxplot of cerebrospinal fluid histamine levels in 36 patients with MS and in 19 healthy controls. The horizontal solid line depict median levels per group. The bottom of the box represents the 25th percentile, the top of the box the 75th percentile. T-bars represent the lowest datum still within 1.5 interquartile range (IQR) of the lower quartile, and the highest datum still within 1.5 IQR of the upper quartile. Dots and stars represent extreme outliers (each symbol represents one patient).