Beginning Anomaly Detection Using

x with a class y. 

Assume that in some context, you are trying to classify whether or not an animal tests 

positive (meaning yes) for some disease. If the animal is diseased and it tests positive, 

this case is a 

true positive. If the animal is healthy and the test shows negative (meaning 

it doesn’t have the disease), then it’s called a 

true negative. However, there are cases 

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where the test can fail. If the animal is healthy but the test says positive, this case is a 

false positive. If the animal is diseased but the test shows negative, this case is a false 

negative.

In statistics, there are similar terms to false positive and false negative: