Hi I'm a CS graduate student

I have a question for AI or data experts. I'm writing a paper

My dataset is time-series sensor data and anomaly (positive class) ratio is between 5% and 6%

you can see the picture below. I used classification_report in sklearn library

enter image description here

But, I'm confused as to what value to report in my evaluation section ...

I think it is reasonable to report f1-score with macro avg (0.40)

Is it ok?

Thank you for your explanation !


1 Answer 1


Classic evaluation metrics are heavily affected by skewed data. In your case, since you have imbalanced data, you should definitely avoid those such as accuracy. For example,

Imagine you have a test data with 100 records. 3 of them have Class A and 97 have Class B. I create this model:

prediction = "B"

Simple as that, I always give the second class. I will get accuracy of 97%, but I fail to predict any of the records I really care.

This is important in cases like cancer prediction where early detection is important.

What you could use instead:

  • Sensitivity
  • Specificity
  • G-Mean
  • F-Measure
  • Class weighted metrics where you give more weight to the smaller one
  • $\begingroup$ Thank you for your explanation ! Um.. Do you think ROC-AUC is also a good measure? $\endgroup$ Jul 7, 2021 at 3:34

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