95% CI (3 stratified bootstrap replicates):
    threshold threshold.low threshold.median threshold.high specificity.low
0.5       0.5           0.5              0.5            0.5               0
0.2       0.2           0.2              0.2            0.2               0
    specificity.median specificity.high sensitivity.low sensitivity.median
0.5                  0                0               1                  1
0.2                  0                0               1                  1
    sensitivity.high
0.5                1
0.2                1
