What is the best way to confirm quality control results according to Quality Assurance principles?

The best way to confirm quality control results according to Quality Assurance principles is to conduct periodic observations of the contractor's testing. This approach emphasizes active monitoring and verification processes, which are critical components of a robust quality assurance framework. By performing regular observations, you can ensure that the testing procedures being employed meet established standards, are executed correctly, and produce reliable results.

Periodic observations allow for real-time assessments and provide opportunities to address any issues or discrepancies before they affect the overall project quality. This hands-on approach fosters accountability and helps maintain the integrity of the testing process.

Utilizing only statistical quality control concepts, trusting contractors' reports, or relying solely on independent contractors may leave gaps in oversight. These methods do not ensure continuous verification and may rely too heavily on individual interpretations or third-party findings, which may not be as thorough or frequent as necessary to uphold quality assurance standards. Hence, conducting direct observations is a more proactive and reliable strategy to ensure the validity of quality control results.