Which statement about controls is NOT true in an experimental setup?

Which statement about controls is NOT true in an experimental setup?

• A. A negative result with a positive control is required to validate the test
• B. With a negative control, a negative result is expected
• C. With a positive control, a positive result is expected
• D. A positive result with a negative control could indicate contamination

Answer: (A)

In an experimental setup, controls show whether the procedure itself is producing effects or if any observed results come from the treatment being tested. A negative control should yield no effect, confirming there’s no unintended activity. A positive control should yield the expected effect, proving the assay can detect it when it’s present. If you get a positive result with a negative control, that suggests contamination or a non-specific signal, which undermines the reliability of the test. The statement that a negative result with a positive control is required to validate the test is not true, because the positive control should produce a positive result to confirm the assay works; a negative result there would indicate the test isn’t functioning properly.

In an experimental setup, controls show whether the procedure itself is producing effects or if any observed results come from the treatment being tested. A negative control should yield no effect, confirming there’s no unintended activity. A positive control should yield the expected effect, proving the assay can detect it when it’s present. If you get a positive result with a negative control, that suggests contamination or a non-specific signal, which undermines the reliability of the test. The statement that a negative result with a positive control is required to validate the test is not true, because the positive control should produce a positive result to confirm the assay works; a negative result there would indicate the test isn’t functioning properly.