Sensitivity Calculator
Calculates sensitivity, the share of diseased cases detected by a test. The form displays TP/(TP+FN) beside sensitivity, using a worked condition that can be recalculated with the labeled inputs.
Set the labeled inputs
Sensitivity
Scope of the sensitivity method
The sensitivity page calculates sensitivity, the share of diseased cases detected by a test.
Sensitivity is limited to the statistical quantity named by the result panel. The sensitivity calculation does not silently add a population, time horizon, causal direction, or decision threshold that is absent from the fields.
The surrounding workflow may also require specificity.
Measurements required for sensitivity
- True positives: For sensitivity, the worked value for true positives is 80 cases. Treat the true positives entry (80 cases) explicitly as a count, proportion, rate, estimate, or model parameter before comparing sensitivity conditions. The form enforces minimum 0.
- False negatives: For sensitivity, the worked value for false negatives is 20 cases. Treat the false negatives entry (20 cases) explicitly as a count, proportion, rate, estimate, or model parameter before comparing sensitivity conditions. The form enforces minimum 0.
The entries used for sensitivity must refer to one coherent analysis condition. Combining incompatible populations, periods, or measurement definitions can produce valid sensitivity arithmetic for a nonexistent study.
How sensitivity is calculated
For sensitivity, match every symbol in the relationship to a labeled field before substituting numbers. Sensitivity is reported in the scale implied by the inputs and formula.
While checking sensitivity, inspect every denominator in TP/(TP+FN). For sensitivity, a zero or near-zero denominator can make sensitivity undefined or unstable.
Checking the displayed example
The default sensitivity condition is True positives = 80 cases, False negatives = 20 cases.
80 true positives and 20 false negatives give sensitivity .80.
The live calculator reports Sensitivity 0.8. Repeating one intermediate step from TP/(TP+FN) provides a fixed sensitivity reference check for later code changes.
Conditions attached to sensitivity
Sensitivity is conditional on disease status and does not answer how many positive results are true.
For sensitivity, diagnostic and risk measures are conditional on named denominators, reference definitions, population prevalence, and follow-up time.
Putting sensitivity beside the study design
When interpreting sensitivity, keep the two-by-two counts or source risks with the result; a ratio alone can hide very different absolute event frequencies.
As a second check for sensitivity, reversing the numerator and denominator answers a different question, so retain the direction printed in TP/(TP+FN).
A controlled sensitivity check for sensitivity
Change true positives while holding the remaining entries fixed, then state why the direction and size of the sensitivity change are plausible from TP/(TP+FN).
Repeat the sensitivity exercise with false negatives. If a modest defensible change materially alters the interpretation, report both conditions rather than presenting that sensitivity scenario as exact.
Input and rounding traps
Before accepting sensitivity, compare every entered value with its label, unit, and allowed domain after reading the printed relationship from left to right.
For sensitivity, do not move a number between fields merely because the units look compatible; each label gives the number a different statistical role.
Another sensitivity failure occurs when a rounded output is reused as though it were the original measurement. Carry guard digits through calculations that depend on sensitivity, then round only the reported value.
Reporting sensitivity reproducibly
Report sensitivity using TP/(TP+FN), followed by the entered values, units, exclusions, and analysis date. Name the sensitivity population or dataset boundary instead of leaving it implicit.
Keep the full calculator output with the record, including Sensitivity 0.8. A later sensitivity review can then distinguish a changed input from a different convention or software implementation.
Questions about sensitivity
What does sensitivity represent on this page?
It is the quantity produced by TP/(TP+FN) from the displayed true positives, false negatives. This page calculates sensitivity, the share of diseased cases detected by a test.
What should be saved with sensitivity?
Save the entered values and units for true positives, false negatives, along with the analysis date, exclusions, software or formula version, and the relationship TP/(TP+FN). That record is sufficient to rebuild this specific sensitivity calculation.