Podcast
Questions and Answers
Which term describes the agreement between your value and the ‘true’ value?
Which term describes the agreement between your value and the ‘true’ value?
- Specificity
- Accuracy (correct)
- Precision
- Sensitivity
Precision refers to the correctness of a single measurement.
Precision refers to the correctness of a single measurement.
False (B)
What is the term used to describe the reproducibility of your results?
What is the term used to describe the reproducibility of your results?
Precision
Accuracy is determined by direct comparison to a __________ value.
Accuracy is determined by direct comparison to a __________ value.
Match the following terms with their definitions:
Match the following terms with their definitions:
What consequence may arise from a lack of specificity in a test?
What consequence may arise from a lack of specificity in a test?
Poor precision can result from poor quality reagents.
Poor precision can result from poor quality reagents.
What is the primary ability of a method that defines its specificity?
What is the primary ability of a method that defines its specificity?
A test's __________ reflects its ability to detect small quantities of a measured component.
A test's __________ reflects its ability to detect small quantities of a measured component.
Match the following terms with their definitions:
Match the following terms with their definitions:
What is a key indicator of precision in measurements?
What is a key indicator of precision in measurements?
Intra-assay precision refers to the reproducibility of results within one test run.
Intra-assay precision refers to the reproducibility of results within one test run.
What are the two ways in which precision is assessed?
What are the two ways in which precision is assessed?
The ideal situation in accuracy and precision is when results are _____ and the mean is close to the ‘true’ value.
The ideal situation in accuracy and precision is when results are _____ and the mean is close to the ‘true’ value.
Which example describes a situation that is imprecise but still accurate?
Which example describes a situation that is imprecise but still accurate?
Labs can efficiently waste resources on repeat runs if they are not achieving acceptable accuracy.
Labs can efficiently waste resources on repeat runs if they are not achieving acceptable accuracy.
What is the significance of having precise test results for a lab?
What is the significance of having precise test results for a lab?
Match each term with its definition:
Match each term with its definition:
What does diagnostic sensitivity refer to?
What does diagnostic sensitivity refer to?
The mean of a normal distribution is also known as the median.
The mean of a normal distribution is also known as the median.
What is the purpose of determining diagnostic specificity?
What is the purpose of determining diagnostic specificity?
The _____ is defined as the square root of the sum of the squared deviations from the mean.
The _____ is defined as the square root of the sum of the squared deviations from the mean.
What does the coefficient of variation indicate?
What does the coefficient of variation indicate?
A high standard deviation indicates that the values are closely clustered around the mean.
A high standard deviation indicates that the values are closely clustered around the mean.
Match the following diagnostic terms with their definitions:
Match the following diagnostic terms with their definitions:
In a normal distribution, values fall randomly about the _____ value.
In a normal distribution, values fall randomly about the _____ value.
What does a lower standard deviation indicate about precision?
What does a lower standard deviation indicate about precision?
68% of all results are expected to fall within ± 2 standard deviations from the mean.
68% of all results are expected to fall within ± 2 standard deviations from the mean.
What is the formula for calculating standard deviation?
What is the formula for calculating standard deviation?
The mean result in this example is _____ mmol/L.
The mean result in this example is _____ mmol/L.
Match the standard deviation range to their corresponding percentages.
Match the standard deviation range to their corresponding percentages.
If the standard deviation is 1.0 mmol/L, what is the range within which 68% of the results fall?
If the standard deviation is 1.0 mmol/L, what is the range within which 68% of the results fall?
Statistically, it is acceptable for 10% of results to fall outside of ± 2 standard deviations from the mean.
Statistically, it is acceptable for 10% of results to fall outside of ± 2 standard deviations from the mean.
The number of results in this example is _____ .
The number of results in this example is _____ .
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Study Notes
Laboratory Performance Analysis
- Accuracy refers to how close a measured value is to the true value.
- Precision describes the reproducibility of measurements, meaning how close repeated measurements are to each other.
- Within-run precision (intra-assay precision) assesses precision within a single analytical run.
- Between-run precision (inter-assay precision) assesses precision across different analytical runs.
- Specificity indicates the ability of a method to measure only the intended analyte, minimizing interference from other substances.
- Sensitivity refers to the method's ability to detect small quantities of the analyte.
Common Quality Control Terms
- Quality Control (QC) involves procedures and processes used to ensure the accuracy and reliability of laboratory results.
Statistical Concepts for Quality Control
- Normal Distribution describes the spread of data points around a central average, known as the mean.
- Standard Deviation (SD) represents the average dispersion of data points from the mean.
- A lower SD indicates better precision.
- Coefficient of Variation (CV) is the ratio of the SD to the mean, expressed as a percentage.
- It provides a standardized measure of precision, regardless of the specific units of measurement.
Interpreting Statistical Data for Precision
- Mean ± 1 SD: Approximately 68% of data points fall within one standard deviation of the mean.
- Mean ± 2 SD: Approximately 95% of data points fall within two standard deviations of the mean.
Solving Precision and Accuracy Problems
- Poor accuracy is often caused by calibration issues, which are usually easier to address.
- Poor precision can have various causes, such as:
- Poor quality reagents
- Improperly maintained instruments
- Inadequate training
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