p.5
Quality Control Statistics and Control Charts
What is the standard deviation (SD) in statistics?
Square root of the variance.
p.4
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is the formula for Negative Predictive Value (PV)?
True negatives / (True negatives + False negatives)
p.9
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is the definition of accuracy in a laboratory setting?
Describes how close a test result is to the true value.
p.6
Quality Control Statistics and Control Charts
What is the most accurate measure of performance affecting laboratory values?
Total imprecision analysis.
p.6
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
Give an example of a pre-analytical error.
Wrong or missing patient identification.
p.4
Quality Control Statistics and Control Charts
What is the mode in a data set?
The most frequently occurring value
p.1
Sources of Variance and Error in Laboratory Procedures
What are the key components of nonanalytical factors in quality assessment?
Qualified personnel, established laboratory policies, laboratory procedure manual, test requisitioning, and preventive maintenance of equipment.
p.8
Quality Control Statistics and Control Charts
What are Westgard Rules used for?
To analyze data in control charts based on statistical methods.
p.9
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is the definition of precision in a laboratory setting?
How close results are to one another.
p.1
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What are the primary sources of laboratory errors?
Preanalytical and postanalytical phases.
p.2
Importance of Quality Control Programs
What does QC documentation include?
Preventive maintenance records, temperature charts, and QC charts.
p.5
Quality Control Statistics and Control Charts
What is a confidence interval?
Range using 2 SD on either side of the mean.
p.6
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
Give an example of an analytical error.
Incorrect sample and reagent volume.
p.4
Quality Control Statistics and Control Charts
How many data points does CLSI recommend for estimating the mean and precision for a control level?
20 data points from 20 or more separate testing runs
p.1
Sources of Variance and Error in Laboratory Procedures
What is the role of qualified personnel in a laboratory?
Perform QC activities, maintain instruments, and keep accurate records.
p.5
Sources of Variance and Error in Laboratory Procedures
What is random error?
Error due to chance, varies from sample to sample.
p.6
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What do pre-analytical errors refer to?
Inappropriate performances before specimens are measured by analyzers.
p.5
Understanding Reference Values and Ranges
What does the term 'reference range' mean?
Range of values that includes 95% of test results for a healthy reference population.
p.6
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What are analytical errors attributed to?
Operator or instrument error.
p.4
Quality Control Statistics and Control Charts
What does standard deviation (SD) measure?
The spread or variability in a data set
p.1
Quality Control Statistics and Control Charts
What do accrediting agencies require for quality control?
Monitoring and documentation of quality assessment records.
p.2
Quality Control Statistics and Control Charts
What is the objective in controlling the reliability of laboratory determinations?
Reject results with more than the permitted amount of error.
p.8
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What is an example of a postanalytical error?
Critical value reporting.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does precision in a procedure refer to?
Repeatability or reproducibility.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What can aid accuracy in laboratory procedures?
Properly standardized procedures, statistically valid comparisons, use of controls, and proficiency testing programs.
p.4
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does a Negative Predictive Value (PV) indicate?
Number of patients with a normal test result who do not have the disease
p.9
Control Specimens and Their Role in Quality Control
What is a control specimen?
Specimen is similar to patient’s blood, known concentration of constituent.
p.9
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does sensitivity refer to in diagnostic testing?
Cases with specific disease or condition produce a positive result.
p.8
Performance Improvement Programs: Six Sigma and Lean Systems
What does a Lean Clinical Laboratory aim to achieve?
Utilizes fewer resources, reduces costs, enhances productivity, promotes staff morale, and improves the quality of patient care.
p.2
Control Specimens and Their Role in Quality Control
Why do clinical laboratories use multiconstituent controls?
Less storage space, ease of inventory, and peer laboratory comparisons.
p.5
Sources of Variance and Error in Laboratory Procedures
What is constant error?
Difference between target value and assayed value, independent of sample concentration.
p.1
Importance of Quality Control Programs
Why is a quality control program important?
To ensure accuracy and precision of test performance over time.
p.2
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does precision describe?
How close the test results are to one another.
p.7
Quality Control Statistics and Control Charts
What is a Youden/Twin Plot used for?
To compare results obtained on high and low control serum from different laboratories.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is prevalence in the context of a disease?
Proportion of a population who has the disease.
p.6
Quality Control Statistics and Control Charts
How is imprecision or random error studied?
By running 2 control solutions twice a day over a 10-to-20-day period.
p.1
Quality Control Statistics and Control Charts
What is the purpose of quality control (QC) in a laboratory?
To detect errors from test system failure, adverse environmental conditions, and variance in operator performance.
p.9
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What is an example of a preanalytical error?
Specimen collected in wrong tube.
p.8
Quality Control Statistics and Control Charts
What does the Shewhart Levey-Jennings Chart represent?
Acceptable limits of variation in the results of an analytic method.
p.5
Sources of Variance and Error in Laboratory Procedures
What is proportional error?
Greater deviation from target value due to higher sample concentration.
p.7
Quality Control Statistics and Control Charts
What type of errors does CUSUM identify?
Consistent bias problems.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
How can precision be expressed?
Standard deviation (SD) or coefficient of variation (CV).
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is specificity in the context of a test?
Proportion of cases with absence of the specific disease that give a negative test result.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does a positive predictive value (PV) indicate?
Number of patients with an abnormal test result who have the disease.
p.6
Quality Assessment and Statistical Evaluations
What are the indicators of analytic performance?
Internal QC, proficiency testing, accreditation, quality assurance monitoring, and laboratory utilization.
p.8
Performance Improvement Programs: Six Sigma and Lean Systems
In Six Sigma, what are defects?
Anything that does not meet customer requirements.
p.8
Performance Improvement Programs: Six Sigma and Lean Systems
How are defects generally measured in Six Sigma?
Per million opportunities (DPMO).
p.8
Performance Improvement Programs: Six Sigma and Lean Systems
What is the primary goal of a Lean System?
Reducing waste (nonvalued activities).
p.2
Control Specimens and Their Role in Quality Control
What is a control specimen?
Material or solution with a known concentration of the analyte.
p.5
Sources of Variance and Error in Laboratory Procedures
What is systematic error?
Error influencing observations consistently in one direction.
p.4
Quality Control Statistics and Control Charts
What can be used to set provisional ranges if 20 runs cannot be completed?
A minimum of seven units (three replicates per run)
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
How can precision be ensured?
Inclusion of standards, reference samples, control solutions, replicate determinations, and duplicate determinations.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is the formula for sensitivity?
True positives / (True positives + False negatives) x 100.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is incidence in the context of a disease?
Number of subjects found to have the disease within a defined period in a population.
p.9
Quality Control Statistics and Control Charts
What is calibration in the context of laboratory procedures?
Comparison of an instrument measure or reading to a known physical constant.
p.4
Quality Control Statistics and Control Charts
What type of curve is used to describe the reference range for a particular measurement?
Normal bell-shaped Gaussian curve
p.1
Quality Control Statistics and Control Charts
What should be included in a written record of QC activities?
Details of deviation from usual results, problems, failures, and corrective actions.
p.2
Quality Control Statistics and Control Charts
What must be done if the QC specimen value is not within the acceptable range?
Review procedure, correct error, and repeat testing.
p.2
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does accuracy describe in clinical quality assessment?
How close a test result is to the true value.
p.2
Importance of Quality Control Programs
What is quality control?
Process that monitors accuracy and reproducibility of results.
p.2
Quality Control Statistics and Control Charts
What are standards?
Highly purified substances of a known composition.
p.9
Quality Control Statistics and Control Charts
What are standards in laboratory procedures?
Highly purified substance of a known composition.
p.1
Sources of Variance and Error in Laboratory Procedures
What should a laboratory procedure manual include?
Comprehensive listing of approved policies, acceptable practices, and precautions.
p.9
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does specificity refer to in diagnostic testing?
Cases without a specific disease or condition produce a negative result.
p.8
Quality Control Statistics and Control Charts
What is the Shewhart Levey-Jennings Chart used for?
It is a QC chart used in clinical laboratories.
p.2
Control Specimens and Their Role in Quality Control
What is the advantage of liquid control materials over lyophilized controls?
Greater reproducibility between bottles.
p.8
Quality Assessment and Statistical Evaluations
What does a Delta Check compare?
Current results with past results of the same analytes on the same individual.
p.7
Quality Control Statistics and Control Charts
What does a Cumulative Sum Graph (CUSUM) calculate?
The difference between QC results and the target means.
p.7
Quality Control Statistics and Control Charts
What is the earliest indication of systematic errors in CUSUM?
When the slope exceeds 45° or a decision (±2.7 SD) is exceeded.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is the formula for specificity?
True negatives / (False positives + True negatives) x 100.
p.6
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
When do post-analytical errors occur?
After the analysis is complete but within the laboratory.
p.1
Quality Control Statistics and Control Charts
What are the key activities involved in quality control (QC)?
Monitoring performance of laboratory instruments, reagents, other testing products, and equipment.
p.7
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What are some common issues related to laboratory results?
Unavailable or delayed results, long turnaround time, incomplete results, wrong transcription, missing results, results submitted to the wrong physician.
p.7
Performance Improvement Programs: Six Sigma and Lean Systems
What does Six Sigma aim to improve?
Process by eliminating variations or errors, improved performance, quality, bottom line, customer satisfaction, and employee satisfaction.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What is sensitivity in the context of a test?
Proportion of cases with a specific disease that give a positive test result.
p.5
Types of Laboratory Errors: Preanalytical, Analytical, and Postanalytical
What is clerical error?
Error with handwritten labels and request forms.
p.2
Quality Control Statistics and Control Charts
What is calibration?
Comparison of an instrument measure to a known physical constant.
p.7
Performance Improvement Programs: Six Sigma and Lean Systems
What is the main goal of Six Sigma?
To reduce the number of defects to near zero.
p.3
Diagnostic Usefulness: Accuracy, Precision, Sensitivity, and Specificity
What does the accuracy of a procedure refer to?
Closeness to true or actual value.
