Hours of option trading at christmas eve
Performance of five risk adjustment models was evaluated from three aspects: statistical indicators, proportions of true cases identified by models and medical utilization of predicted cases. Statistical indicators included c-statistics, sensitivity and predictive positive value (PPV), 1 and the thresholds for calculating statistical indicators were set as the corresponding levels of outcomes.
The c-statistic represents the area under the receiver operating characteristic curve, and hence provides an overall measure of model performance. Actual 2005 top users were assigned to one of four mutually exclusive categories ( Supplementary data, Appendix D ): in the 2004 top user group alone (area c ), in predicted top user group identified by risk adjustment models alone (area a ), in both groups (area b ) or in neither group.