Simple Example To Understand True Positives, True Negatives, False Positives and False Negatives

Do you have difficulty differentiating between true positive, true negative, false positive and false negative? Well, let me walk you through all 4 with a simple instance.

The simple illustration

Let's say there is a spreading disease called the Bad Syndrome (BS). Taking a population sample, every individual is either sick with the disease or healthy (not neither, not both).

Being the genius you are, you created a system to test for the BS disease. so every individual would either test positive for the BS disease or negative (not neither, not both).

Ideally, all sick people should equal all who test positive for the disease but the world is not perfect.

So, when someone tests POSITIVE for BS and TRULY has the BS disease, that's true positive (meaning that the positive test is true).

When someone tests POSITIVE for BS but does NOT have the BS, that's a false alarm which is false positive (meaning that the positive test is wrong).

When someone tests NEGATIVE for BS and TRULY does NOT have the BS, that's true negative (meaning the negative test is true).

When someone tests NEGATIVE for BS but does HAVE the BS in reality, that's false negative (meaning the negative test is wrong).

Easy, isn't it.