Calculate negative likelihood ratio using clear diagnostic inputs. View instant results, tables, and exports now. Learn formulas, steps, examples, and interpretation for better decisions.
The negative likelihood ratio shows how much a negative test result lowers disease odds.
LR- = (1 - Sensitivity) / Specificity
Sensitivity = TP / (TP + FN)
Specificity = TN / (TN + FP)
Post-test Odds = Pre-test Odds × LR-
Probability = Odds / (1 + Odds)
Lower LR- values are better. Values below 0.1 usually show strong rule-out power.
| Case | TP | FN | TN | FP | Sensitivity | Specificity | LR- |
|---|---|---|---|---|---|---|---|
| Example A | 80 | 20 | 90 | 10 | 0.800000 | 0.900000 | 0.222222 |
| Example B | 95 | 5 | 85 | 15 | 0.950000 | 0.850000 | 0.058824 |
| Example C | 70 | 30 | 88 | 12 | 0.700000 | 0.880000 | 0.340909 |
Negative likelihood ratio is a useful diagnostic measure. It helps evaluate negative test results. It combines sensitivity and specificity into one value. This makes interpretation clearer. Lower values mean better rule-out strength. Clinicians, analysts, and students often use it.
The calculator supports two methods. First, you can enter TP, FN, TN, and FP. The script then derives sensitivity and specificity. Second, you can enter sensitivity and specificity directly. Both methods return LR-. Additional outputs improve insight. These include false negative rate, accuracy, and negative predictive value.
An LR- below 0.1 is usually very strong. It suggests a negative result greatly lowers disease probability. Values near 0.2 still provide meaningful evidence. Values above 0.5 are weaker. Values near 1 provide little change. The calculator labels this automatically. That saves time during review.
Pre-test probability matters in real decisions. A negative result affects each patient differently. The same LR- can lead to different post-test probabilities. This calculator converts probability into odds. It then applies LR-. Finally, it converts odds back into probability. That gives a more practical conclusion.
This tool also helps teaching and reporting. You can test scenarios quickly. You can compare tables easily. The CSV export supports spreadsheet work. The PDF option supports printable summaries. The layout stays simple and clean. It works well across screens. That makes it useful for study, audits, and presentations.
It measures how much a negative test result reduces the odds of a condition. Smaller values show better ability to rule out disease.
Values below 0.1 are usually strong. Values between 0.1 and 0.2 are still helpful. Values close to 1 are weak.
Yes. Use the direct mode. Enter sensitivity and specificity percentages, and the calculator will compute LR- immediately.
It affects the post-test probability after a negative result. The same LR- gives different clinical meaning at different starting risks.
The formula becomes undefined because division by zero is not allowed. The calculator returns N/A in such cases.
No. False negative rate is 1 minus sensitivity. LR- divides that value by specificity, so it includes both major diagnostic components.
Yes. It includes an example table, supporting metrics, formulas, and export options, which makes it useful for assignments and revision.
CSV is useful for spreadsheets and records. PDF is useful for printing, sharing, and attaching clean result summaries.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.