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I have 3 different confusion matrices, with data in them. Initially, I was just going to analyze the data using specificity and sensitivity, however I stumbled upon a ROC curve which has plots for FP and TP.

Problem is, I don't really understand how to plot it with the data I have?

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  • $\begingroup$ Possible duplicate of ROC of multi-class classification from confusion matrix only $\endgroup$
    – famargar
    Jan 22, 2018 at 10:08
  • $\begingroup$ To plot the ROC curve, you need the predicted 'probabilities' from your model (as opposed to the predicted classes). Three confusion matrices is not enough. Do you have access to that? i.e. how did you create your model / get those confusion matrices in the first place. $\endgroup$
    – Dan
    Jan 22, 2018 at 10:27

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You cannot construct a ROC curve from the confusion matrix alone, or a few confusion matrix. A confusion matrix is a single point in your ROC curve, and you need all possible confusion matrices at all thresholds to build a full curve and compute the AUC.

This is what I wrote in an other answer. The question was about multiclass ROC curves, but the answer is the same.

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  • $\begingroup$ if it is the same answer, why not comment and provide link? $\endgroup$
    – Haitao Du
    Apr 21, 2017 at 13:35
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    $\begingroup$ @hxd1011 Not sure what you mean, I did give the link, didn't I? $\endgroup$
    – Calimo
    Apr 21, 2017 at 15:03

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