The Likelihood Ratio is used to communicate how likely it is that a person has a specific condition based on a positive result from the test being performed. The ratio is calculated by taking the probability that a patient with a specific condition will have a certain result on a given test and dividing it by the probability that a patient without that specific condition will have a given result on the same test. Likelihood ratios can be either positive or negative depending on whether you are describing the likelihood based on a positive test result or the likelihood based on a negative test result. LR of 1 or lower generally means there is little probability that a patient has the condition being tested for. LR of 1 is non-informative. It essentially is of no diagnostic value. LR of greater than one means it is likely that a patient has the condition. The higher above 1, the more likely the patient has the condition being tested for.