URI: http://www.qualityml.org/1.0/metrics/PositivePredictiveValue
Name: Positive Predictive Value
Alternative names: PPV

In statistics and diagnostic testing, the positive predictive value, or precision rate is the proportion of positive test results that are true positives (such as correct diagnoses). It is a critical measure of the performance of a diagnostic method, as it reflects the probability that a positive test reflects the underlying condition being tested for. Its value does however depend on the prevalence of the outcome of interest, which may be unknown for a particular target population. The PPV can be derived using Bayes' theorem.


where FP = false positive, TP = true positive

Parameters: actual categories
Source: GeoViQua
Categories: Thematic accuracy
Further information: http://en.wikipedia.org/wiki/Sensitivity_and_specificity
XML schema:
<schema xmlns:qml="http://www.qualityml.org/1.0" 
xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.qualityml.org/1.0" 
elementFormDefault="qualified" attributeFormDefault="unqualified">
<import namespace="http://www.uncertml.org/2.0" schemaLocation="../../uncertml/2.0/uncertml.xsd"/>

	<element name="PositivePredictiveValue" type="qml:ContinuousValuesSummaryStatisticType" substitutionGroup="un:AbstractSummaryStatistic"/>
XML example:
JSON example:
API example:
Value constraints: categories: any string
counts: any positive natural number