Which of the following is considered an example of alternate proficiency testing?

Alternate proficiency testing is a method used to evaluate the accuracy and reliability of laboratory results by comparing them with results obtained from another source. In this context, split samples sent to another facility using the same test method represent a direct comparison between two laboratories. By analyzing the same sample under identical conditions, laboratories can ascertain their performance relative to one another. This arrangement effectively assesses consistency and reliability in test results, which aligns perfectly with the goals of proficiency testing.

Other options, while related to laboratory quality assurance, do not qualify as alternate proficiency testing. Internal quality control focuses on maintaining standards within the laboratory itself and does not involve external validation or comparison with other laboratories. External validation of test methods is a separate process that addresses the accuracy of methodologies rather than ongoing proficiency testing among laboratories. Routine laboratory audits are designed to assess compliance with regulations and standards rather than proficiency in test performance across facilities.