Table 1.

Statistics on the area under the ROC curves for detection of internal masqueraders and external masqueraders using our immunity-based method, the single-sensor HMM method and the uniqueness method.

Method	Masquerader	Mean	Standard deviation	95% confidence interval
Immunity-based	Internal	0.04456	0.01001	0.04394 – 0.04518
HMM	Internal	0.09442	0.01537	0.09347 – 0.09538
Uniqueness	Internal	0.06435	0.01002	0.06373 – 0.06435
Immunity-based	External	0.07375	0.01009	0.07312 – 0.07438
HMM	External	0.09481	0.01526	0.09386 – 0.09575
Uniqueness	External	0.07839	0.01004	0.07776 – 0.07902