What describes an R4s error in QC?

An R4s error in quality control (QC) indicates a specific type of pattern observed in control charts. This error is characterized by six consecutive results being on the same side of the mean, violating the expected randomness in normal distributions. It reflects poor performance as it suggests there is a systematic bias affecting the results.

This systematic trend can signal a problem with the assay or measurement process, demonstrating that the control data is increasingly deviating from the mean range, thereby warranting investigation into the source of error. Understanding R4s errors is crucial for maintaining the accuracy and reliability of laboratory results.

Recognizing this type of error allows laboratory personnel to take corrective actions before the issue affects patient results. Other options do not describe the pattern associated with an R4s error directly: consecutive controls exceeding ±2s suggests potential outliers, comparing means between methods addresses method validation, and the algebraic difference between controls relates to variability rather than trends consistent with R4s.