= 0.965 (96.5%). For calculating a relative sensitivity or specificity it must be assumed that one test is the gold standard or reference For the purposes of the calculation this test is assumed to have perfect sensitivity and specificity. If we take test A as the reference then there were 248 positive sera of which test B only identified 225 as positive therefore the sensitivity of test B relative to test A is: Relative sensitivity (B to A) = 225/248 = 0.907 (90.7%). Similarly according to test A are 1,344 negative sera and the specificity of test B relative to test A is Relative specificity (B to A) = 1,312/1344 = 0.976 (97.6%). In the above example the overall agreement between the tests was reasonably high (0.965) and there is no evidence that the tests are fundamentally different. Therefore, it could just as well be argued that test B should be used as the reference test. In this case relative sensitivity and specificity become: Relative sensitivity (A to B) = 225/257 = 0.875 (87.5%) Relative specificity (A to B) = 1312/1335 = 0.983 (98.3%) There are no defined rules for interpretation of relative test results. Overall agreement and relative specificities and sensitivities calculated with both tests taken as reference should be considered when comparing two tests. The term precision encompasses both repeatability and reproducibility. Precision describes the ability to repeatedly perform tests in a manner that consistently gives the same results. The characteristic can be likened to the performance of a marksman. If the marksman places all his shots in close proximity to each other his precision is good even if they are not near the bulls-eye. Someone shooting with good repeatability may score lower than a person who scatters shots around the target and gets some in the bulls-eye. However, high precision is the preferable characteristic because by simply adjusting the rifle sights the shooter with high precision can place all shots near the bulls-eye to get an excellent score.
= 0.965 (96.5%). For calculating a relative sensitivity or specificity it must be assumed that one test is the gold standard or reference For the purposes of the calculation this test is assumed to have perfect sensitivity and specificity. If we take test A as the reference then there were 248 positive sera of which test B only identified 225 as positive therefore the sensitivity of test B relative to test A is: Relative sensitivity (B to A) = 225/248 = 0.907 (90.7%). Similarly according to test A are 1,344 negative sera and the specificity of test B relative to test A is Relative specificity (B to A) = 1,312/1344 = 0.976 (97.6%). In the above example the overall agreement between the tests was reasonably high (0.965) and there is no evidence that the tests are fundamentally different. Therefore, it could just as well be argued that test B should be used as the reference test. In this case relative sensitivity and specificity become: Relative sensitivity (A to B) = 225/257 = 0.875 (87.5%) Relative specificity (A to B) = 1312/1335 = 0.983 (98.3%) There are no defined rules for interpretation of relative test results. Overall agreement and relative specificities and sensitivities calculated with both tests taken as reference should be considered when comparing two tests. The term precision encompasses both repeatability and reproducibility. Precision describes the ability to repeatedly perform tests in a manner that consistently gives the same results. The characteristic can be likened to the performance of a marksman. If the marksman places all his shots in close proximity to each other his precision is good even if they are not near the bulls-eye. Someone shooting with good repeatability may score lower than a person who scatters shots around the target and gets some in the bulls-eye. However, high precision is the preferable characteristic because by simply adjusting the rifle sights the shooter with high precision can place all shots near the bulls-eye to get an excellent score.