Which plot is used to monitor systematic QC performance across time?

Which plot is used to monitor systematic QC performance across time?

• A. Instrument throughput
• B. Random errors only
• C. Sample collection times
• D. Systematic QC performance

Answer: (D)

Monitoring systematic QC performance across time is done with a control chart that plots QC results against time, showing how measurements compare to a target with established limits. The classic form, a Levey-Jennings plot, places a central target line and control limits (derived from the method’s standard deviation) so you can see shifts in the mean (bias) or changes in spread (precision) over time. This directly reveals systematic issues in the testing process, rather than random scatter or unrelated metrics like throughput or collection times. So, this plot type is the one that tracks systematic QC performance over time.

Monitoring systematic QC performance across time is done with a control chart that plots QC results against time, showing how measurements compare to a target with established limits. The classic form, a Levey-Jennings plot, places a central target line and control limits (derived from the method’s standard deviation) so you can see shifts in the mean (bias) or changes in spread (precision) over time. This directly reveals systematic issues in the testing process, rather than random scatter or unrelated metrics like throughput or collection times. So, this plot type is the one that tracks systematic QC performance over time.