False positive = (Machine says positive but grand truth is negative) / (Machine says is positive)
In English, a false positive is when the machine declares something as positive but it is actually negative.
This fits a sanity test because ~50% of people that pass through a detector do not get patted down. The truth is closer to 10%. Even then, a true positive probably includes someone with two pennies in their pocket.
False positive = (Machine says positive but grand truth is negative) / (Machine says is positive)
In English, a false positive is when the machine declares something as positive but it is actually negative.
This fits a sanity test because ~50% of people that pass through a detector do not get patted down. The truth is closer to 10%. Even then, a true positive probably includes someone with two pennies in their pocket.