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MTDB Quality Measures

MTDB Quality Measures. Scott Fifield Chief, Geographic Process and Quality Management Branch Quality, Assessments, and Evaluations Work Group Chair. Spatial Update Quality. Every edge in the MTDB has a Means ID (MID) based on authority, task, and source

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MTDB Quality Measures

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  1. MTDB Quality Measures Scott Fifield Chief, Geographic Process and Quality Management Branch Quality, Assessments, and Evaluations Work Group Chair

  2. Spatial Update Quality • Every edge in the MTDB has a Means ID (MID) based on authority, task, and source • MIDs are a compact way to track a number of metadata records and attributes • The Spatial Census Quality Value (CQV) ranks the feature type-specific quality of a source (via a formula)

  3. Spatial Update Quality • Circular Error 95% (CE95) – we calculate CE95 for a source based on a sample of points – 95% fall within 7.6m of the GPS control points • Only sources that meet the minimum standards are used for update

  4. Ongoing Quality Checks • Business Rules run at time of update • Business Rules run as a batch each morning • MT Edits run periodically to check relationships between fields and legal values • Institutionalize the stand-alone edit checks – find errors as early in the process as we can

  5. Quality Checks at Benchmarking • We benchmark the MTDB twice each year • After all updates in a county complete, the county is locked and a series of edits run • We restrict these edits to the data needed for this cycle of products

  6. Sequence of Pre-Benchmark Edits • Validate Topology • Business Rules and Legal Values • Validate Geometry • Geographic Area Validation and Reconciliation

  7. The Next Stage • Define quality – “fitness for use” (Juran, 1951) or the “degree to which a set of inherent characteristics fulfills (customer) needs or expectations” • Recommendation written to develop spatial and geographic area quality indicators • Store quality data on the primitive level (edge, elemental feature) where appropriate

  8. The Next Stage • QIs include: Spatial Accuracy, Coverage, Name/Attribute Completeness/Accuracy • Standard reporting unit will be tract – what is the quality for the various indicators • Ingest all quality data into the Confidence Analysis and Tracking Tool (CATT) • By tract – where do we have confidence, where do we have deficiencies?

  9. Questions? • scott.p.fifield@census.gov • 301-763-3556

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