Dayvid, as I said, this metric should be called "balanced accuracy" (BA) to
avoid misunderstandings with the real AUC from the ROC curve as stated in the
given reference. I also had my autocorrection on: 1 - FP_rate = TN_rate and BA
= (TP_rate+TN_rate)/2. It is not "another" but the same evaluation metric with
your formula.
Using AUC for this might result in wrong expectations as for example it was
done in the old WEKA implementation, where no real AUC was calculated but the
BA. Sometimes "simplified AUC" or "one point AUC" is used, too, but BA is
shorter and avoids misunderstandings.
The concept of the balanced accuracy can be also generalized to an arbitrary
number of classes. If the geometric mean is used instead of the arithmetic
mean, the metric is called "G-Mean". It is a little less intuitive but is more
sensitive to different rates and can be generalized to more than two classes as
well.
G-Mean = sqrt(TP_rate x TN_rate)
On 23.07.2014, at 19:46, Dayvid Victor <victor.d...@gmail.com> wrote:
> Mario, as I said, the correct would be:
> AUC = (1 + TP_rate - FP_rate) / 2
>
> But you are also right, that is another evaluation metric stated in those
> references I sent!
>
>
>
>
> On Wed, Jul 23, 2014 at 2:06 PM, Mario Michael Krell <kr...@uni-bremen.de>
> wrote:
> 1-FN_rate = TN_rate
>
> Concequently, (1 + TP_rate - FN_rate)/ 2 should be named "Balanced Accuracy"
> to avoid misunderstandings. Nevertheless, it is a good choice.
>
>
> On 23.07.2014, at 18:57, Dayvid Victor <victor.d...@gmail.com> wrote:
>>
>> Or you might use the trapezoid aproximation: auc = (1 + TP_rate - FN_rate)/ 2
>>
>
>
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> --
> Dayvid Victor R. de Oliveira
> PhD Candidate in Computer Science at Federal University of Pernambuco (UFPE)
> MSc in Computer Science at Federal University of Pernambuco (UFPE)
> BSc in Computer Engineering - Federal University of Pernambuco (UFPE)
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