This chapter describes standardized test method precision and bias performance metrics adopted by ASTM D02 and associated standard practices to quantify these metrics. General and statistical interpretation of these metrics is described. An overview discussion with reference to a standard practice on how to use statistical quality assurance and control charting techniques to monitor these metrics is provided. The concept of relative bias between test methods is discussed with reference to a standard practice on how to assess and correct for this relative bias. Knowledge of these performance metrics can drive standard test method and practice improvements via technical revisions through the consensus standard development process, continuous improvement of workplace specific practices, and improve confidence of the product quality information represented by test method results, thus facilitating efficient and effective commerce between supplier and consumer. Standard practices prescribing statistical methodology for how to account for testing imprecision in adjudicating product quality disputes is also referenced.