Working out 2 group signal detection diagnostics
The area under Receiver Operating Characteristic (ROC) curves is a way of describing the magnitude of how well separated two groups are with respect to some diagnostic.
For two groups where the mean of A > mean of B it is a plot of sensitivity at each of T thresholds (Probability of being in group A given you have a value less than or equal to t) against 1 - specificty (probability of being in group B given you have a value less than or equal to t) as seen [rocplot.jpg: here].
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True |
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A |
B |
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X |
<= t |
a |
b |
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> t |
c |
d |
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