PPV From Sensitivity and Base Rate Calculator
Bayes PPV from independently applicable sensitivity, specificity, prevalence base-rate fractions; undefined zero-positive probability refused, not diagnostic certainty. Actual independently qualified instrument/cohort/matching units; no diagnosis, causal outcome, validated personal prediction or universal clinical cutoff.
Description
Positive predictive value depends on sensitivity, specificity and prevalence.
Positive predictive value depends on sensitivity, specificity and prevalence.1
Even a strong test can have a different predictive value in a population with a different base rate. The calculation and input requirements are explained below.
When to use PPV From Sensitivity and Base Rate Calculator
Enter sensitivity, specificity and applicable base rate as fractions from 0 to 1.
How to use PPV From Sensitivity and Base Rate Calculator and how it works
- Prepare the measurements or independently established model inputs described below, with matching units and observation scope.
- Enter the required fields and run PPV From Sensitivity and Base Rate Calculator.
- Read the result fields using the formula, output units, signs and ordering explained below.
- Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualSensitivity | Actual Sensitivity. Use the units and matching context stated in the calculation below. | number | Required; fraction from 0 to 1; finite; other constraints below |
| actualSpecificity | Actual Specificity. Use the units and matching context stated in the calculation below. | number | Required; fraction from 0 to 1; finite; other constraints below |
| callerApplicableBaseRate | Caller Applicable Base Rate. Use the units and matching context stated in the calculation below. | number | Required; fraction from 0 to 1; finite; other constraints below |
Enter sensitivity, specificity and applicable base rate as fractions from 0 to 1. Compute true-positive mass and false-positive mass, require their sum positive, and divide true-positive mass by that sum. A zero total positive probability is an error rather than a defined PPV.
PPV=sensitivity*baseRate/(sensitivity*baseRate+(1-specificity)*(1-baseRate)) Apply the input ordering, units and branch conditions stated above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the calculated or selected fields below. | object |
| result.value | Numeric result under the formula and output units explained above. | number |
{
"input": {
"actualSensitivity": 0.8,
"actualSpecificity": 0.8,
"callerApplicableBaseRate": 0.2
},
"output": {
"result": {
"value": 0.5000000000000001
}
}
}Limitations and assumptions
The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.
All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.
Alternative or Complementary methods
Use PCL-5 Cutoff Checker for a complementary operation: PCL-5 screening interpretation requires the assessment context and chosen criteria.
Use ASRS Part A Screener Cutoff Checker for a complementary operation: ASRS Part A screening interpretation depends on the instrument's scoring and clinical context.
References
Similar or alternative tools
- PCL-5 Cutoff Checker
PCL-5 screening interpretation requires the assessment context and chosen criteria.
- ASRS Part A Screener Cutoff Checker
ASRS Part A screening interpretation depends on the instrument's scoring and clinical context.