Likelihood Ratios for Microbiology

Inferences for Likelihood Ratios

Likelihood ratios are extensively used to evaluate the performances of diagnostic tests and to update prior odds of disease to posttest odds. Since few tests are truly 100% accurate, including many used as “gold standards,” it is important to be able to estimate likelihood ratios in cases where no such standard is available. In this paper, methods to calculate point and interval estimates for l...

Likelihood ratios for DNA identification.

Likelihood ratio (LR) tests are provided for the three alternatives to DNA identity: exclusion, coincidence, and kinship. The coincidence test uses the radius of coalescence to conserve the observed frequency of single band phenotypes. Genotype probabilities under kinship are derived for mating groups, specified relatives, and structured populations; and unbiased estimates of the genetic parame...

Score-based likelihood ratios for handwriting evidence.

Score-based approaches for computing forensic likelihood ratios are becoming more prevalent in the forensic literature. When two items of evidential value are entangled via a scorefunction, several nuances arise when attempting to model the score behavior under the competing source-level propositions. Specific assumptions must be made in order to appropriately model the numerator and denominato...

The trouble with likelihood ratios.

ity scale for clinicians is symmetrically skewed in both directions. In primary care, elective surgery, and oncology, clinicians work at the extremes of the probability scale. The time has come to apply the Feynman-Tufte principle to clinical logic, to offer a visual representation of Bayesian logic. Earlier attempts with natural logarithmics do not allow a simple graphic. We teach a scale of l...

Simplified calculations using likelihood ratios.