likelihood ratio


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Related to likelihood ratio: confidence interval, Likelihood ratio test, Positive predictive value

likelihood ratio

usually preceded by "maximum" (that is, maximum likelihood ratio), this ratio maximizes the probability that the parameters in the ratio agree with the empirically observed data.

like·li·hood ra·ti·o

(līk'lē-hud rā'shē-ō)
The ratio of the probability of a test result among patients with a certain disease or disorder to the probability of that same test result among patients who do not have the targeted disease or disorder.

likelihood ratio

(līk′lē-hood″),

LR

A statistical tool used to help determine the usefulness of a diagnostic test for including or excluding a particular disease. An LR = 1 suggests that the test ordered neither helps to diagnose the disease in question nor helps to rule it out. Higher LRs increase the probability that the disease will be present; LRs < 1.0 decrease the probability that the disease is present.

A positive LR can be thought of as the probability that someone with a suspected condition will, accurately, have a positive test result, divided by the probability that a healthy person will, inaccurately, test positive for the disease. Mathematically this can be represented by the following equation: LR+ = sensitivity of the test/ (1− specificity of the test). A negative LR is the probability that a sick person will fail to be detected by the test, divided by the probability that a healthy person will be accurately shown by the test to have no sign of disease. Mathematically: LR− = (1 − sensitivity of the test) / specificity of the test.

likelihood ratio

The percentage of ill people with a given test result divided by the percentage of well people with the same result. Ratios near unity should not influence decisions. This useful guide to refining clinical diagnosis is little used mainly because of its complexity; The Fagan nomogram can simplify the matter.
References in periodicals archive ?
Reconceptualizing the burden of proof as a likelihood ratio test
The Fisher exact test demonstrated that subjects' perceptions of the malalignment might serve as a good indicator for the coronal angular malalignment with likelihood ratios of 4.
1992, "The Likelihood Ratio Test under Nonstandard Conditions: Testing the Markov Switching Model of GNP," Journal of Applied Econometrics 7, S61-S82.
For predicting stillbirth, the combination of elevated MSAFP and inhibin A levels had the highest positive likelihood ratio of any of the markers individually and in combination by far (15.
Likelihood ratio tests were performed to test for differences in growth among the different substituted combinations of length-at-age data.
1, X is smaller than or equal to Y in likelihood ratio (reversed hazard rate) ordering sense if, and only if, 0 < [lambda] [less than or equal to] [[lambda].
Positive Likelihood Ratio (LR+) The likelihood that a given positive test result would be expected in a patient with the target disorder compared with the likelihood that the same result would be expected in a patient without that disorder.
In each case, the likelihood ratio remains unchanged.
When all tests were positive, the positive likelihood ratio of 16.
The present study has evaluated HCS in field setting and found its performance satisfactory (high positive likelihood ratio and low negative likelihood ratio) to know anaemia load in the community (high sensitivity and specificity) and also for clinical practice (high positive predictive and negative predictive values).
2] = likelihood ratio statistic for the model with interactions and all main effects, and [LRS.
The goodness-of-fit for the calibrated model can be assessed by the likelihood ratio index ([[rho].