Categorical Data Analysis Using The SAS® System, 2nd Edition

2.6. Sensitivity and Specificity

Some other measures frequently calculated for 2 × 2 tables are sensitivity and specificity. These measures are of particular interest when you are determining the efficacy of screening tests for various disease outcomes. Sensitivity is the true proportion of positive results that a test elicits when performed on subjects known to have the disease; specificity is the true proportion of negative results that a test elicits when performed on subjects known to be disease free.

Often, a standard screening method is used to determine whether disease is present and compared to a new test method. Table 2.9 contains the results of a study investigating a new screening device for a skin disease. The distributions for positive ...