What is meant by a false positive result and what is a false negative result? (Anti-HIV ELISA)?

Also, which error do you think is a greater public health risk and why?


Please tell me the following questions related to (Anti-HIV ELISA)

Let's say you do a search for the name of somebody in a database, or do a test for the presence of some disease in a person.

The search does not find the person in the database or the test results come back that the person does not have the disease. However, that person IS in the database but because you searched including his middle name (which wasn't in the database) the search program said he wasn't there. In the case of the test for a disease, it came back negative but perhaps it was still in the incubation period. A slogan for testing STD diseases is a positive is a positive but a negative is a maybe.

Both the above examples are examples of false negatives. For a person who might have a disease, this can be a major health problem.

A false positive is just the opposite. You find the name of a person in the database but you don't know the person is not who you seek, or you get a positive test for a disease because of unknown factors or even human error. In these cases, eventually you may discover you have the wrong person, and in the disease test, subsequent tests may all prove negative.

False positive: the test tells you you're HIV but you're not. False negative: the test tells you you're not HIV, but you are.

False negative is worse.

With the false positive, you get scared, you probably decide to re-take the test to be sure, and it comes back negative, you take it a third time, negative, ok, you're relieved, not much harm done.

False negative: you think you are not HIV, while in reality you are. You might contaminate other people, you won't seek treatment, etc. And because you're happy the test came back negative, you don't retake it.

A well designed test should give you much less false negative than false positive.