Data Quality, Metadata, Standards, and Governance
This domain tests whether you can judge and document fitness for use: the quality elements and how to measure them, the metadata standards that record them, and the governance controls that keep data trustworthy over time.
Quality elements
- Positional accuracy: how close coordinates are to truth, reported as RMSE or a confidence statement.
- Attribute accuracy: correctness of non-spatial values, often estimated from a sample against reference sources.
- Logical consistency: topological and format integrity, such as no dangling nodes, no self-intersections, no duplicate identifiers.
- Completeness: both coverage (are all areas represented?) and attribute completeness (are required fields populated?).
- Temporal accuracy and currency: how well timestamps reflect real-world change.
- Lineage: the documented history of sources, transformations and processes.
- Semantic accuracy and resolution: whether classifications mean what they claim, at a stated scale.
Metadata and standards
ISO 19115 describes geographic metadata and ISO 19157 describes quality reporting; FGDC CSDGM is the older US content standard; Dublin Core is general-purpose and too thin for spatial lineage. OGC standards cover services: WMS (imagery), WFS (features), WCS (coverage), WMTS (tiles). The ISO 19100 series covers reference systems and geometry.
Governance
Governance covers stewardship, access control, licensing and data-sharing agreements, versioning, retention schedules, QA/QC gates and change logs. A dataset without a named steward and a licence is a liability, not an asset.
Worked example
A road network claims 100% completeness. Sampling 50 random 1 km squares against recent imagery finds roads missing in 4 squares, and 12% of segments lack a surface-type value. Reasoning: the claim conflates coverage with attribute completeness. Coverage is about 92% by sample, attribute completeness about 88%, and the metadata should report both, with the sampling method and date. Reporting a single figure would be misleading and would fail an audit.
Traps that cost marks
- Treating accuracy and precision as synonyms; a coordinate can be precisely wrong.
- Assuming metadata is optional paperwork rather than the record of fitness for use.
- Reporting completeness without stating whether coverage or attributes were measured.
- Confusing a web map service (WMS) with a feature service (WFS).