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A slate magnifying glass over a grid of teal squares, three squares under the lens turned amber and one left as an empty outline

Data quality for GIS

Five audits a professional runs before trusting a layer: identifiers, coordinates against geometry, probable duplicates, completeness against a second layer, and the fitness of a boundary polygon for assignment.

Data Management

Steps
5
Each assumes the one before it
Time
~3 h
At the problems' own estimates
XP
1,120
Before hint costs and speed bonuses
Progress
0/5
Start the pathBegins with Which airport codes will break the schedule join?

What you will be able to do

Audit a dataset before using it — find the missing, malformed and duplicated keys, measure where attributes disagree with geometry, test one layer's completeness against another, and decide with numbers whether a polygon layer is fit to derive attributes from.

The sequence

Each step assumes the one before it.

  1. Up nextWhich airport codes will break the schedule join?Up nextAudit a registry's identifiers before they become a join key: missing, malformed and duplicated codes, and positions that are only approximate.beginnerDifficulty: beginner130 XP~25 min
  2. 2When the attributes and the geometry disagreeA reference gazetteer carries a latitude and a longitude column beside its geometry. Audit how far apart they are, and what else does not add up.intermediateDifficulty: intermediate200 XP~35 min
  3. 3Which ports in the registry are the same port?Find probable duplicates in a facility registry by combining a name match with a distance rule — and separate them from the honest homonyms.intermediateDifficulty: intermediate190 XP~30 min
  4. 4Which big cities does the gazetteer not know?Test one layer's completeness against another: large urban footprints with no populated place inside them at all.advancedDifficulty: advanced300 XP~45 min
  5. 5Are these country polygons fit to assign cities to?A point-in-polygon audit that exposes what 1:50m generalisation does to a coastline — and which places the attribute and the geometry disagree about.advancedDifficulty: advanced300 XP~45 min

Where it leads

Data Management is examined in the Spatial SQL — Associate, which issues the Kharita Certified Spatial SQL (Associate) (KSQL-A1). The problems here are the practice; the assessment is the same kind of problem, under time.