What type of QC problem is indicated by six consecutive control results showing the same trend?

When six consecutive control results show the same trend, this indicates a systematic change in the process. A trend refers to a consistent increase or decrease in control results over time, reflected in these consecutive measurements. It suggests that there is a gradual drift in the analytical method, which could be caused by factors such as instrument instability, changes in reagent performance, or gradual contamination.

Recognizing trends is critical in quality control as they can indicate underlying problems with the analytical method or instrumentation that need to be addressed promptly. In contrast, a shift would imply a sudden change in the results but not a continuous pattern as seen in the six consecutive results. Random error refers to variations that can occur due to unpredictable factors, and kurtosis pertains to the shape of the distribution of results rather than the trends observed in quality control data. Thus, the identification of a trend is essential to maintain the reliability and accuracy of laboratory results.