Likelihood Ratio Calculator

Posted by Dinesh on

Online likelihood ratio calculator to calculate the value of performing a diagnostic test of patient's expected and target disorder in diagnostic testing.

Estimate how the likelihood ratio changes the probability
Likelihood RatioApproximate Change in ProbabilityEffect on Posttest Probability of disease
Values between 0 and 1 decrease the probability of disease
0.1-45%Large decrease
0.2-30%Moderate decrease
0.5-15%Slight decrease
10%None
Values greater than 1 increase the probability of disease
10%None
215%Slight increase
530%Moderate increase
1045%Large increase

Calculate Likelihood Ratios in Diagnostic Testing

Disease
PresentAbsent
TestGiven
Not given
LR+
LR?

Formula:

LR+ = (a/(a+c)) / (b/(b+d))
LR? = (c/(a+c)) / (d/(b+d))

where,
T+ = result of the test is positive,
T? = result of the test is negative,
D+ = present disease,
D? = absent present,
LR+ = Positive likelihood ratio,
LR? = Negative likelihood ratio