Question

a positive control is a sample known to give positive results for the given test. what is the purpose of a positive control? a) give positive results even when the procedure is not optimized b) verify that the negative results are valid c) always give negative results d) validate false-positive results

Explanation:

• Option a: A positive control is known to give positive results. If the procedure is working (even if not optimized), it should give a positive result. But the main purpose of a positive control is to ensure the test can detect the target (so if the positive control doesn't give a positive result, the test is flawed). However, let's analyze other options.
• Option b: A positive control's purpose is to verify that the test can produce a positive result, which in turn helps validate that negative results (when samples are negative) are valid (because if the positive control works, then a negative result is likely true negative, not due to a faulty test).
• Option c: A positive control is supposed to give positive results, not negative, so this is incorrect.
• Option d: False - positive results are errors, and a positive control doesn't validate false - positives. It's about validating the test's ability to detect positives and thus validate negatives.

So the correct answer is b.

Answer:

b) Verify that the negative results are valid