Are the following steps to calculate the accuracy correct or not?. Also, regarding to the sensitivity and specificity, should I do the same?

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FAS 2018-2-5

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https://ww2.mathworks.cn/matlabcentral/answers/380872-are-the-following-steps-to-calculate-the-accuracy-correct-or-not-also-regarding-to-the-sensitivit

评论： FAS 2018-2-6

I have a video clip that contains1500 frames. I trained my algorithm using a training video and detected the abnormalities in these frames. Thus, I have the detected frames which are logical frames and the ground truth dataset, which also is also logical frames. Now, I want to calculate the accuracy and ROC curve. I used the confusion function in this link (https://www.mathworks.com/matlabcentral/fileexchange/46035-confusionmatstats-group-grouphat-?focused=5540014&tab=function), which gives me the accuracy, sensitivity, and specificity. I applied the function to each row in the frame, then to each frame in the video to calculate the average accuracy.

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Rik 2018-2-6

Does it make sense to you in your case to calculate metrics for each row? if so, then there is nothing wrong with what you did.

Do you have some metric that has more than 2 possible values, so you need to find an optimal threshold to call something abnormal? If so, use that metric to make an ROC curve, if not, you can't make one.

Accuracy in the sense that we are using now has a very specific meaning that may or may not be useful for you to calculate. If this is a project where you can ask a supervisor for useful metrics, I advise you to do so.

FAS 2018-2-6