perfcurve and ROC curve
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I have a confusion about ROC curve and hopefully you can help me!
To plot ROC, i was naively using a simple command as plot(False_alarm_rate,Hit_rate,'-'). But, it is not exactly the same as perfcurve plot. To use this function, i wrote the following script
Labels=; Labels = ones(size(Q,1),1);
Labels(end/2+1:end) = 0;
PosClass = 1;
[X Y T,AUC] = perfcurve(Labels,Q,PosClass);
figure, plot(X,Y,'r') % ROC
could you please tell me , what i am missing here?
- BTW, can we calculate d-prime from output of perfcurve?
thanks in advance, Karlo
Ilya on 23 Feb 2016
Q must be classification scores. What you put in Q sounds more like what perfcurve should return as output. Take a classifier from the Statistics and Machine Learning Toolbox such as decision tree, discriminant etc and look at the predict method. The second output from the predict method is classification score.