likelihood ratio


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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 ?
Shepherd, "DbEmpLikeGOF: An R package for nonparametric likelihood ratio tests for goodness-of-fit and two-sample comparisons based on sample entropy," Journal of Statistical Software, vol.
Table 5 demonstrate the value of the likelihood ratio statistic after the element is incorporated inside the model.
Again, we can get fancy and place the odds and the likelihood ratio on a logarithmic scale.
* Once a weight and a likelihood have been determined for each scenario of the observed evidence, the likelihood ratio is given as the sum of the products of the likelihood and the corresponding prior weight for each scenario in the guilty set divided by the sum of the products of the likelihood and the corresponding prior weight for each scenario in the not guilty set.
In this situation the approach based on confidence sets using likelihood ratio tests can be used.
Likelihood Ratio Chi-Square value###1890###1802###1839###1663###1721
This lemma shows the importance of the likelihood ratio or the noise distribution function.
For respected simulation study the processes for both models it can be seen that empirical likelihood ratio test confirmed that it has some mild size disturbance mainly for the small sample size which likely caused by the limiting distribution of .
Difference between readings using HemoCue[TM] and HCS, and accuracy of HCS at different cutoff levels of haemoglobin (n=501) Parameter Less than or Less than or equal to 12 g/dL equal to 10 g/dL Sensitivity 0.96 (CI 0.93-0.98) 0.74 (CI 0.65-0.81) Specificity 0.22 (CI 0.15-0.3) 0.84 (CI 0.8-0.87) PPV 0.75 (CI 0.71-0.79) 0.56 (CI 0.47-0.64) NPV 0.69 (CI 0.53-0.81) 0.92 (CI 0.89-0.95) Likelihood ratio (positive) 1.23 4.63 Likelihood ratio (negative) 0.18 0.31 Efficiency 75% 82% Correlation coefficient 0.7 0.75 Parameter Less than or equal to 7 g/dL Sensitivity 0.83 (CI 0.51-0.98) Specificity 0.99 (CI 0.97-0.98) PPV 0.71 (CI 0.43-0.9) NPV 0.99 (CI 0.98-1.0) Likelihood ratio (positive) 83 Likelihood ratio (negative) 0.17 Efficiency 99% Correlation coefficient 0.87
The score had a sensitivity of 91.9%, a specificity of 79.0%, and a positive likelihood ratio of 4.39 for diagnosis of appendicitis.
The sensitivity, specificity, PPV, NPV, and likelihood ratio positive and likelihood ratio negative of falciparum and vivax arm have been calculated using 2x2 table with Peripheral blood smear as gold standard (Tables 2, 3 and 4).