A quantity used to test nested hypotheses. Let H' be a nested hypothesis with n' degrees of freedom within H (which has n degrees of freedom), then calculate the maximum likelihood of a given outcome, first given H', then given H. Then LR = [likelihood H']/[likelihood H]. Comparison of -2 ln(LR) to the critical value of the chi-squared distribution with n - n' degrees of freedom then gives the significance of the increase in likelihood.

negative likelihood ratio | sensitivity | specificity