Table 2.
Results of adding six measurement error structures on the likelihood ratio (LR) and diagnostic odds ratio (OR) for a brucellosis c-ELISA used in 126 infected and 656 uninfected cattle and water buffalo of Trinidad over four categories of proportion inhibition (PI). Results calculated over 10,000 iterations of the Monte Carlo simulation.
| Error structure | Result category (PI) | No. infected* | No. uninfected* | LR* (90% Interval†) | LR difference* | OR* (90% Interval†) | OR difference* |
| None | <0.25 | 8 | 586 | 0.070 | NA | 1.0 | NA |
| (standard) | 0.25 – 0.349 | 5 | 38 | 0.675 | NA | 9.64 | NA |
| 0.35 – 0.499 | 11 | 17 | 3.32 | NA | 47.4 | NA | |
| ≥0.50 | 102 | 5 | 105 | NA | 1494 | NA | |
| Normal | <0.25 | 8 | 522 | 0.083 (0.051, 0.116) | 0.013 | 1.0 (referent) | NA |
| (0, 0.12) | 0.25 – 0.349 | 5 | 80 | 0.337 (0.136, 0.630) | -0.337 | 4.14 (1.36, 9.90) | -5.50 |
| 0.35 – 0.499 | 9 | 34 | 1.33 (0.72, 2.32) | -1.99 | 16.35 (7.37, 35.8) | -31.0 | |
| ≥0.50 | 103 | 9 | 59.2 (40.2, 105) | -45.3 | 749 (431, 1415) | -745 | |
| Lognormal | <0.25 | 8 | 469 | 0.089 (0.049, 0.133) | 0.019 | 1.0 (referent) | NA |
| 0.12 | 0.25 – 0.349 | 5 | 100 | 0.244 (0.088, 0.485) | -0.430 | 2.79 (0.78, 7.57) | -6.85 |
| 0.35 – 0.499 | 9 | 64 | 0.707 (0.338, 1.42) | -2.61 | 8.13 (3.10, 21.5) | -39.3 | |
| ≥0.50 | 104 | 11 | 49.4 (23.8, 104) | -55.2 | 582 (239, 1288) | -913 | |
| Normal | <0.25 | 9 | 543 | 0.088 (0.057, 0.122) | 0.018 | 1.0 (referent) | NA |
| (0.1, 0.12) | 0.25 – 0.349 | 6 | 71 | 0.427 (0.181, 0.801) | -0.247 | 4.89 (1.69, 11.7) | -4.74 |
| 0.35 – 0.499 | 10 | 26 | 1.83 (0.98, 3.24) | -1.49 | 21.2 (9.70, 44.6) | -26.2 | |
| ≥0.50 | 101 | 6 | 86.3 (53.3, 171) | -18.3 | 994 (580, 1980) | -501 | |
| Normal | <0.25 | 7 | 499 | 0.078 (0.046, 0.113) | 0.008 | 1.0 (referent) | NA |
| (-0.1, 0.12) | 0.25 – 0.349 | 5 | 90 | 0.264 (0.101, 0.506) | -0.410 | 3.44 (1.03, 8.89) | -6.20 |
| 0.35 – 0.499 | 8 | 43 | 0.954 (0.488, 1.66) | -2.36 | 12.5 (5.25, 28.2) | -34.9 | |
| ≥0.50 | 105 | 13 | 41.8 (28.6, 66.7) | -62.8 | 555 (321, 1065) | -939 | |
| Normal | <0.25 | 10 | 444 | 0.120 (0.068, 0.176) | 0.049 | 1.0 (referent) | NA |
| (0, 0.24) | 0.25 – 0.349 | 4 | 89 | 0.254 (0.089, 0.496) | -0.421 | 2.14 (0.61, 5.56) | -7.50 |
| 0.35 – 0.499 | 8 | 79 | 0.540 (0.267, 0.966) | -2.78 | 4.59 (1.85, 10.8) | -42.8 | |
| ≥0.50 | 103 | 34 | 15.7 (10.7, 24.7) | -88.9 | 135 (73.0, 270) | -1359 | |
| Lognormal | <0.25 | 10 | 401 | 0.124 (0.065, 0.192) | 0.054 | 1.0 (referent) | NA |
| 0.24 | 0.25 – 0.349 | 3 | 75 | 0.237 (0.062, 0.500) | -0.438 | 1.91 (0.43, 5.44) | -7.72 |
| 0.35 – 0.499 | 7 | 99 | 0.366 (0.169, 0.675) | -2.95 | 3.00 (1.11, 7.62) | -44.4 | |
| ≥0.50 | 105 | 68 | 7.81 (4.68, 16.1) | -96.8 | 67.0 (30.1, 167) | -1427 | |
*Median value of Monte Carlo simulations. †Interval formed as the 5th and 95th percentiles of Monte Carlo simulations.
NA = not applicable.