How to use the diagnostic likelihood ratio calculator
Find how much a positive or negative test result changes the odds of disease, from sensitivity and specificity. Enter sensitivity, specificity in the fields above; the positive likelihood ratio, negative likelihood ratio are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “likelihood ratio positive negative”, “LR+ LR-”, “test likelihood ratio”, “calculate diagnostic likelihood ratio”, “find positive likelihood ratio”.
Formula
Variables
- sens — Sensitivity
- spec — Specificity
Worked example
With sensitivity = 0.9, specificity = 0.85, the calculator gives positive likelihood ratio ≈ 6; negative likelihood ratio ≈ 0.1176471.
Frequently asked questions
What is the diagnostic likelihood ratio calculator used for?
Find how much a positive or negative test result changes the odds of disease, from sensitivity and specificity. It helps with questions such as “likelihood ratio positive negative”, “LR+ LR-”, “test likelihood ratio”.
What is the formula for the diagnostic likelihood ratio calculation?
Positive likelihood ratio = sens / (1-spec). Negative likelihood ratio = (1-sens) / spec. Here sens is sensitivity, spec is specificity.
What inputs do I need for the diagnostic likelihood ratio calculator?
You need sensitivity, specificity. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the diagnostic likelihood ratio calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the diagnostic likelihood ratio result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.