Following our last blog post, today, we will show how to calculate binary agreement using the Analyse-it Method Validation edition. The CLSI EP12: User Protocol for Evaluation of Qualitative Test Performance protocol is a useful companion resource for laboratories and diagnostic companies developing qualitative diagnostic tests.
In Analyse-it, you should arrange the data in frequency or case form, as discussed in the blog post: Using Analyse-it to establish the diagnostic accuracy (sensitivity/specificity) of a COVID-19 test. You can find an example of both and follow the steps below, using the workbook COVID-19 Agreement Example.xlsx.
The analysis task pane opens.
NOTE: The Average method is useful when comparing two laboratories or observers where neither is considered a natural comparator. The reference method is asymmetric, and the result will depend on the assignment of the X and Y methods, whereas the average method is symmetric, and the result does not change when swapping the X and Y methods.
INFO: Older versions of Analyse-it do not support the Average method, and the Agreement by category checkbox is called Agreement.
The analysis report shows positive and negative agreement statistics.
The positive agreement is 93.2%, and the negative agreement is 86.0%. You can see from the contingency table that the Comparative method identified 59 positives and 43 negatives, whereas the Test method identified 61 positives, 41 negatives. There are 55 positive agreements, 37 negative agreements, and 4 disagreements where the Comparative method is positive and the Test method negative, 6 disagreements where the Comparative method is negative and the Test method positive.
The agreement plot is a visual representation of the agreement:
For more information, see our online documentation:Agreement measures for binary and semi-quantitative dataAgreement plotEstimating agreement between two binary or semi-quantitative methods
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