Good manufacturing practice recommends that a test instrument be _______ times more accurate than the unit under test.

Good manufacturing practice suggests that a test instrument should be at least four times more accurate than the unit it is testing. This guideline is in place to ensure that any measurements taken are reliable and that the test instrument can adequately detect any errors or deviations in the unit under test.

The rationale behind this recommendation is based on the need to minimize measurement uncertainty. By using a more accurate instrument, the test results can provide a clear comparison against the specified standards or tolerances of the unit being tested. If the test instrument were only marginally more accurate, it may not effectively reflect the true performance of the unit, potentially leading to undetected issues or flawed assessments.

Having a test instrument that is significantly more accurate allows for better quality control and assurance, ultimately leading to improved product reliability and compliance with industry standards.