The likelihood ratio for a negative test is defined as the probability of a negative test result given that the disease is present, divided by the probability of a negative test result given that the disease is absent. It is calculated using the formula:
LR- = (1 - Sensitivity) / Specificity
Here, sensitivity is the true positive rate, and specificity is the true negative rate. A lower LR- value suggests that a negative test result is more effective in ruling out the disease.
