Other Names - Accuracy, Bias Test, Correctness Verification, Accuracy Assessment, Method Accuracy Evaluation, Bias Measurement, Correctness Validation, Accuracy Verification, Bias Analysis, Method Accuracy Check.
Trueness is one of the primary MV experiments. It involves comparing your instrument’s actual results with those an EQA qualified sample. The mechanism is similar to Method Comparison, but compares actual results with highly validated results for comparison. Few samples may be used for comparison due to stringent sample requirements.
What is the Trueness Experiment?
The Trueness Experiment assesses the accuracy of a measurement method, indicating how close the average of a series of test results is to the true value of the analyte. High trueness means that the method produces results that are consistently accurate and free from systematic errors or bias. This is crucial for ensuring the reliability and validity of diagnostic tests.
The Trueness Experiment involves comparing the test results from the method being verified against known reference values or a gold standard.
External Quality Assessments (EQAs) and Interlaboratory Comparisons (Interlab) are integral to evaluating trueness. In EQAs, samples are distributed to multiple laboratories to assess their performance and ensure accuracy. Interlab comparisons involve multiple laboratories testing the same samples and comparing their results to ensure consistency and accuracy across different settings.
Cualia Trueness has a limit of max 10 samples. They should be of high EQA validity.
Cualia Recommendations: Verifications: Quantitative 1-5 samples. Qualitative 1-5 samples. Validations/LDTs: 3-10 samples
2. Sample Selection
For Trueness in Method Verification (MV), sample selection is crucial and should involve using gold standard samples that have been validated and agreed upon by multiple sources, such as External Quality Assessments (EQA) and Interlaboratory Comparisons (Interlab). These samples ensure that the method’s accuracy is assessed against the highest standards, providing a reliable benchmark for trueness evaluation.
3. Testing Samples
Measure each sample on a new instrumentation (actual). Record the results in comparison with the gold standard reference values, label and source either in the Cualia app or on your own platform. Include the label and the source.
4. Use the Cualia MV App
Make sure the data is entered into the experiment with the right acceptance criterias.
Data Table
There are 5 relevant columns in the Qualitative Trueness Data Table:
Label | Free text - The general identification used to identify a specific Sample.
Source | Free text - The original source of the Sample such as Patient, EQA, or the name of the Manufacturer
Actual | Pos or Neg Label only - Represents the real-world value measured by the instrument being evaluated.
Reference | Pos or Neg Label only - The true value as measured from the reference method.
Result | Read Only - Indicates whether the measurements are within agreeable range.
Qualitative Trueness Results
Name | Definition |
|---|---|
Min. Samples | An Acceptance Criteria of the minimum number of eligible samples required in order for the evaluation’s requirements to be fulfilled. |
Min. Agreement | The minimum percentage of agreement required between the test results and the reference results from the acceptance criteria for the experiment to pass. |
Sample(s) | Individual specimens collected for testing representing the source. In MV experiments with Runs, this can refer to to the number of concentration levels used. |
Agreement | Whether two values, usually the actual and reference values acceptably agreeable, based on testing requirements and/or Error Allowance. |
Agreements | The total number of measurements between actual and reference value in agreement. |
Agreement Percent | The percentage (%) of paired Results within Agreement amongst the number of Samples measured. |
True Positive (TP) | The number of true positive results where the test correctly detected the presence of the substrate when compared to the reference method. |
True Negative (TN) | The number of true negative results where the test correctly identified the absence of the substrate when compared to the reference method. |
False Positive (FP) | The number of false positive results where the test incorrectly detected the presence of the substrate when compared to the reference method. |
False Negative (FN) | The number of false negative results where the test incorrectly missed the presence of the substrate when compared to the reference method. |
Sensitivity (Qualitative) | The ability of the test to correctly identify true positives. |
Specificity (Qualitative) | The ability of the test to correctly identify true negatives. |
Negative Predictive Value (NPV) | The proportion of negative test results that are true negatives. |
Positive Predictive Value (PPV) | The probability that a Positive Result indicates the Expected analyte Result is a positive. |
Qualitative Trueness Acceptance
When both samples and agreement values satisfy the acceptance criterias, the experiment will be in a Passed state indicated with a green check.