CMT Laboratory Quality Control and Management 2 — Questions and Answers
Question 1: Which statistical measure describes the spread of data points around the mean in a quality control dataset?
- Coefficient of variation
- Standard deviation (Correct answer)
- Median
- Mode
Correct answer: Standard deviation
Standard deviation (SD) measures the dispersion or spread of data points around the mean and is the foundation of QC limit setting.
Question 2: On a Levey-Jennings chart, warning limits are most commonly set at:
- ±1 SD from the established mean
- ±2 SD from the established mean (Correct answer)
- ±3 SD from the established mean
- ±4 SD from the established mean
Correct answer: ±2 SD from the established mean
Levey-Jennings charts typically display warning limits at ±2 SD and rejection limits at ±3 SD from the established mean.
Question 3: What is the correct action when a QC failure occurs during a laboratory testing run?
- Report patient results and document the QC failure in the log afterward
- Repeat the QC test and report patient results if the repeat passes
- Hold patient results, investigate the cause, correct the problem, rerun QC, and then report results (Correct answer)
- Notify the laboratory director and wait indefinitely for further instructions
Correct answer: Hold patient results, investigate the cause, correct the problem, rerun QC, and then report results
Upon QC failure, patient results must be held, the cause investigated, corrective action taken, and QC must pass before patient results are reported.
Question 4: What is the primary purpose of a 'delta check' in laboratory quality management?
- Verifying instrument calibration against a reference standard
- Comparing a patient's current result with their previous result to detect unexpected changes (Correct answer)
- Assessing QC trends over time using Levey-Jennings charts
- Evaluating the performance of new reagent lots before use
Correct answer: Comparing a patient's current result with their previous result to detect unexpected changes
Delta checks compare a patient's current laboratory result with a previous result to detect specimen identification errors or clinically unexpected changes.
Question 5: Which type of analytical error causes all test results to consistently shift in one direction away from the true value?
- Random error
- Proportional error
- Systematic error (Correct answer)
- Gross error
Correct answer: Systematic error
Systematic error causes a consistent, directional shift of all results from the true value, affecting accuracy while precision may be maintained.
Question 6: According to CLIA regulations, how often must calibration verification be performed for quantitative laboratory tests?
- Daily before patient testing begins
- Weekly on a fixed schedule
- Every 6 months or when specified by the manufacturer (Correct answer)
- Annually during laboratory inspection
Correct answer: Every 6 months or when specified by the manufacturer
CLIA regulations require calibration verification at least every 6 months, whenever calibration is performed, or as recommended by the manufacturer.
Question 7: What is the primary function of a Laboratory Information System (LIS) in quality management?
- To automatically generate and analyze QC charts in real time
- To track reagent lot numbers and expiration dates
- To manage, store, and accurately transmit patient and QC data (Correct answer)
- To perform delta checks on all patient results across departments
Correct answer: To manage, store, and accurately transmit patient and QC data
The LIS manages and stores patient and QC data, facilitates result transmission to clinicians, and supports overall laboratory workflow and documentation.
CMT Laboratory Quality Control and Management 2
Which statistical measure describes the spread of data points around the mean in a quality control dataset?