Patient-Based Real-Time Quality Control (PBRTQC) uses the statistical characteristics of a particular patient population(s) served by a laboratory using specific analytical platforms. There is a review of this approach in the August 2019 issue of Clinical Chemistry. The power of these techniques is that they offer exquisite customization to provide very sensitive detection of a change in bias. They are not subject to the impact of noncommutability issues and, once set up, are low cost to maintain. However, they do require knowledge of the characteristics of the laboratory patient population(s) and the analytical methods used. PBRTQC needs to be tailored for each measurand in a population, though this is certainly not a major limitation. Optimization requires access to simulation software and patient data from the Laboratory Information System.