10 Questions
What is the Levey-Jennings Chart used to graph?
Successive QC results
What does good control results on a Levey-Jennings Chart look like?
Evenly distributed QC values about the mean and within +/- 1 SD limits
What constitutes a systematic error shift on a Levey-Jennings Chart?
6 consecutive results lying on the same side of the mean within +2SD limits
When should an analytical run be rejected based on QC values?
If just 1 QC value is outside 2SD but within the 3SD limit
What does a trend on a Levey-Jennings Chart indicate?
Gradual loss of reliability of the test system
What is the main cause of a systematic error shift on a Levey-Jennings Chart?
Changes in reagent
How many consecutive results lying on the same side of the mean indicate a systematic error shift on a Levey-Jennings Chart?
6
In what situation should an analytical run not be rejected based on QC values on a Levey-Jennings Chart?
Just 1 QC value is outside 2SD but within the 3SD limit
What does a trend on a Levey-Jennings Chart indicate?
Gradual loss of reliability of the test system
When are test results still considered in-control on a Levey-Jennings Chart?
If QC values are within +2SD limits and there are no shifts or trends
Study Notes
Levey-Jennings Chart
- Used to graph quality control (QC) data over time, allowing for the detection of trends and shifts in analytical performance.
Good Control Results
- Randomly scattered around the mean, with an equal number of points above and below the mean.
- No systematic pattern or trends, indicating analytical performance is within acceptable limits.
Systematic Error Shift
- A consistent deviation from the mean, indicating a problem with the analytical process.
- Constituted by 7 or more consecutive results lying on the same side of the mean.
- Typically caused by a problem with the instrument, reagents, or analytical technique.
Rejecting an Analytical Run
- An analytical run should be rejected if the QC values exceed the acceptable limits or show a systematic error shift.
- Rejection is necessary to prevent erroneous results from being reported.
Trend Identification
- A trend on a Levey-Jennings Chart indicates a gradual change in analytical performance over time.
- May be due to instrument drift, reagent degradation, or other factors, and requires corrective action.
Analytical Run Acceptance
- An analytical run should not be rejected based on QC values if the results are within acceptable limits and show no systematic error shift.
- Results are still considered in-control if the QC values are within the acceptable range and show no trends or shifts.
Test your knowledge of data handling and method evaluation with this quiz on Levey-Jennings charts. Learn about interpreting QC values, identifying shifts, and understanding systematic errors. Master the concepts necessary for ensuring accurate and reliable test results.
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