Likelihood ratio: Difference between revisions
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imported>Robert Badgett (New page: In diagnostic tests, the '''likelihood ratio''' is the likelihood that a clinical sign is in a patient with disease as compared to a patient without disease. Compari...) |
imported>Robert Badgett m (→Calculations) |
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Likelihood ratios are relatived to [[sensitivity and specificity]]. | Likelihood ratios are relatived to [[sensitivity and specificity]]. | ||
The positive likelihood ratio (LR+) | The positive likelihood ratio (LR+) measures the likelihood of a finding being ''present'' in patient with the disease. A large LR+, for example a value more than 10, helps rule in disease.<ref name="pmid12213147">{{cite journal |author=McGee S |title=Simplifying likelihood ratios |journal=J Gen Intern Med |volume=17 |issue=8 |pages=646–9 |year=2002 |month=August |pmid=12213147 |doi= |url= |issn=}}</ref> | ||
<math>\text{LR+} = \frac{\text{sensitivity}}{(1-\text{specificity})}</math> | <math>\text{LR+} = \frac{\text{sensitivity}}{(1-\text{specificity})}</math> | ||
The negative likelihood ratio (LR-) measures the | The negative likelihood ratio (LR-) measures the likelihood of a finding being ''absent'' in patient with the disease. A small LR-, for example a value less than 0.1, helps rule out disease.<ref name="pmid12213147">{{cite journal |author=McGee S |title=Simplifying likelihood ratios |journal=J Gen Intern Med |volume=17 |issue=8 |pages=646–9 |year=2002 |month=August |pmid=12213147 |doi= |url= |issn=}}</ref> | ||
<math>\text{LR-} = \frac{(1-\text{sensitivity})}{\text{specificity}}</math> | <math>\text{LR-} = \frac{(1-\text{sensitivity})}{\text{specificity}}</math> | ||
==References== | ==References== | ||
<references/> | <references/> | ||
Revision as of 10:47, 1 April 2009
In diagnostic tests, the likelihood ratio is the likelihood that a clinical sign is in a patient with disease as compared to a patient without disease. Comparing likelihoods (or odds) is different than comparing percentages. (or probabilities).
Calculations
Likelihood ratios are relatived to sensitivity and specificity.
The positive likelihood ratio (LR+) measures the likelihood of a finding being present in patient with the disease. A large LR+, for example a value more than 10, helps rule in disease.[1]
The negative likelihood ratio (LR-) measures the likelihood of a finding being absent in patient with the disease. A small LR-, for example a value less than 0.1, helps rule out disease.[1]
References
- ↑ 1.0 1.1 McGee S (August 2002). "Simplifying likelihood ratios". J Gen Intern Med 17 (8): 646–9. PMID 12213147. [e]