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OS MasterMap data measures

This table gives you the generic definitions of the ways we measure the data in our products.

Data MeasureDefinitionSub-measureDefinition
CompletenessPresence and absence of features against the specified data contentOmissionFeatures representing objects that conform to the specified data content but are not present in the data
CommissionFeatures representing objects that do not conform to the specified data content but are present in the data
Logical consistencyDegree of adherence to logical rules of data structure, attribution and relationshipsConceptual consistencyHow closely the data follows the conceptual rules (or model)
Domain consistencyHow closely the data values in the dataset match the range of values in the dataset specification
Format consistencyThe physical structure (syntax): How closely the data stored and delivered fits the database schema and agreed supply
Topological consistencyThe explicit topological references between features (connectivity)- according to specification
Positional accuracyAccuracy of the position of featuresAbsolute accuracyHow closely the coordinates of a point in the dataset agree with the coordinates of the same point on the ground (in the British National Grid reference system)
Relative accuracyPositional consistency of a data point or feature in relation to other local data points or features within the same or another reference dataset
Geometric fidelityThe ‘trueness’ of features to the shapes and alignments of the objects they represent
Temporal accuracyAccuracy of temporal attributes and temporal relationships of featuresTemporal consistencyHow well ordered events are recorded in the dataset (Lifecycles)
Temporal validity (Currency)Validity of data with respect to time: The amount of real-world change that has been incorporated in the dataset that is scheduled for capture under current specifications
Thematic accuracy (Attribute accuracy)Classification of features and their attributesClassification correctnessHow accurately the attributes within the dataset record the information about objects

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© Ordnance Survey 2019