Fig. 3. Classifier performance.

Predicting sickness given the physiological signs: a with five-fold validation, the AUC is 0.77 ± 0.018. Data from day −21 to day −8 were treated as negative cases, while data from day +1 to day +7 were assumed positive. Data from day −7 to day 0 were ignored. Day 0 was the day when symptoms were reported. The sensitivity is 0.259 ± 0.059 at 99% specificity, 0.437 ± 0.037 at 95% specificity, and 0.513 ± 0.034 at 90% specificity. b The fraction of users predicted positive on specific days, from day −30 to day +14, for specificity requirements of 99% (magenta), 95% (blue), and 90% (brown). Errors bars are 1 standard deviation.