If you are looking for 5 people out of a population of 2,000,000, then a system that was 99.98% accurate at identifying them would would have a 98% false positive rate - it would pick out 250 people, and your 5 suspects would be among them.
If you are looking for 5 people out of a population of 2,000,000, then a system that was 99.98% accurate at identifying them would would have a 98% false positive rate - it would pick out 250 people, and your 5 suspects would be among them.