Attach attributes and audit missing data
See this course’s project requirements
Compare an existing and proposed service location in the supplied fictional four-zone town.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- Define the decision and geographic layers with aggregate data.
- Plot a labeled coordinate grid and check units.
- Join attributes by zone ID and document missing-data checks.
- Calculate baseline and closure routes from the given network.
- Compare unique coverage and deliver a map, table and scoped memo.
Review and revise
Use these criteria to check your work and choose what to improve.
- Geographic meaning: layers, units and assumptions are explicit.
- Data quality: IDs and populations match without invented values.
- Calculation: route and unique coverage arithmetic is reproducible.
- Communication: the map supports a limited, accessible decision explanation.
Want more background?
The idea in everyday life
A map can look convincing even when a table is joined to the wrong places. Names may differ across sources, and missing values can be painted as zero by accident. You will join the town’s population table by zone ID and inspect the match count. This keeps the later coverage arithmetic connected to the correct geographic features.
Geometry gives a map feature its location and shape. Its attribute table holds facts about that feature, which must be checked before use.
One step at a time.
Use the sample or information you have permission to use. Keep your work as you go. You can pause between steps.
- 1
Write the geometry IDs A, B, C and D beside the four points. Create a separate attribute table using the same IDs and the populations 30, 20, 40 and 10.
- 2
Match each table row to its point by ID, not by visual position or row number. Confirm that every zone has exactly one population record and no ID occurs twice.
- 3
Add fictional table row E=25 without an E geometry. Record it as unmatched rather than discarding it silently or attaching it to whichever point has space nearby.
- 4
In a separate test copy, replace D’s population with unknown. Explain that total population is then incomplete, rather than reporting 90 as the whole town’s population.
- 5
Restore the original fixture for the final project and save a quality log containing the match check, unmatched-row test and missing-value interpretation. Record when the counts were defined and their fictional origin.
See how it works.
Fictional join check: geometry IDs A,B,C,D match attribute rows A=30, B=20, C=40 and D=10, giving four matches and a total of 100. If the table is sorted D,C,B,A, the result should stay the same because the join uses IDs. An extra E=25 remains unmatched and needs explanation. If D is unknown, the known counts sum to 90, but the overall population is not established. The map should label unknown values distinctly rather than coloring D as an empty zone. In this project, the original complete fixture is retained for the route comparison.
Did you cover these?
- Four original IDs match exactly once.
- Extra E is flagged as unmatched.
- Unknown D is distinguished from population zero.
What to finish
A matched attribute table and a three-part data-quality log.
Watch for this
Joining by row order or converting missing values into zero without evidence.
How can I tell I understand it?
Keep totals and match counts consistent when table order changes.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.
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Sources and further reading
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Source & access notes · checked 2026-09-10
Opened via Penn State’s course link and read the feature/attribute distinction. Public OER page; its noncommercial share-alike license is not treated as permission to copy exercises.
Access: Free public reading; no account or certificate is required for this Life Starter course.
Reuse: Linked for reference. Examples, activities and assessments here are original; free access alone does not grant permission to reuse source text or branding.
Source & access notes · checked 2026-09-10
Read point, line, polygon, scale, geometry, layer and attribute explanations in official QGIS 3.44 documentation.
Access: Free public reading; no account or certificate is required for this Life Starter course.
Reuse: Linked for reference. Examples, activities and assessments here are original; free access alone does not grant permission to reuse source text or branding.
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