Which statement best describes the purpose of the 2x2 contingency table in diagnostic testing?

Which statement best describes the purpose of the 2x2 contingency table in diagnostic testing?

• A. It measures the agreement between two raters.
• B. It estimates the odds ratio for association.
• C. It estimates risk ratio for a binary outcome.
• D. It summarizes diagnostic test performance using TP, FP, FN, TN.

Answer: (D)

In diagnostic testing, a 2x2 contingency table is used to summarize how well a test performs by organizing the test results (positive or negative) against the actual disease status (present or absent). The four cells represent true positives, false positives, false negatives, and true negatives. From this layout you can calculate sensitivity (how good the test is at identifying disease when it is present) and specificity (how good it is at ruling out disease when it is absent), as well as predictive values and likelihood ratios. This makes the table the most direct summary of diagnostic test performance because it explicitly anchors each possible outcome to both the test result and the true condition. The other concepts described by the other options refer to agreement between raters, measures of association, or incidence comparisons, which are not what the 2x2 table is designed to summarize.

In diagnostic testing, a 2x2 contingency table is used to summarize how well a test performs by organizing the test results (positive or negative) against the actual disease status (present or absent). The four cells represent true positives, false positives, false negatives, and true negatives. From this layout you can calculate sensitivity (how good the test is at identifying disease when it is present) and specificity (how good it is at ruling out disease when it is absent), as well as predictive values and likelihood ratios. This makes the table the most direct summary of diagnostic test performance because it explicitly anchors each possible outcome to both the test result and the true condition. The other concepts described by the other options refer to agreement between raters, measures of association, or incidence comparisons, which are not what the 2x2 table is designed to summarize.