Fig. 2. Urine neopterin time-series covering a period of 63 days. Both the raw neopterin data (black line) as well as the fit from the ARIMA model representing the series’ internal structure (gray line) are plotted. The 300-µmol urine neopterin level, which has been determined to be a significant predictor of SLE activity, is indicated by the dotted line. The data represent the mean of three independent determinations.