Domain 3 — Performing Analysis (20%)¶

Roughly 15 of 75 questions. Tool-knowledge heavy: when to use Buffer, Clip, Intersect, Union, Erase, Spatial Join, Near, Select by Attributes, Select by Location.

What's tested¶

3.1 Finding geographic locations¶

The Locate pane (Map ribbon → Locate) lets you find places by:

You can also use the Map ribbon → Bookmarks to save and return to extents.

Geocoding¶

A separate, more powerful workflow that converts a table of addresses into points.

• Geocode Addresses geoprocessing tool, or Geocoding ribbon → Geocode Addresses.
• Requires a locator (a service or local file).
• Output: a point feature class with match status (Matched, Tied, Unmatched).
• You can Rematch unmatched results in an interactive table.

Common exam patterns¶

• "How to find a coordinate on the map?" → Locate pane
• "How to convert a CSV of addresses to points?" → Geocode Addresses (with a locator)
• "How to rerun an unmatched geocode?" → Rematch / interactive rematch

3.2 Selection — interactive¶

The Map ribbon → Select tool, or its drop-down:

Selection options¶

• New selection (default) — replaces.
• Add to current selection (hold Shift).
• Remove from current selection (hold Ctrl).
• Select from current selection.

Switch / Clear / Zoom To¶

On the Map ribbon → Selection group or right-click a layer in Contents:

• Clear — empty the selection.
• Switch — invert the selection.
• Zoom To Selection — fit the map to selected features.

3.3 Select by Attributes¶

A SQL-driven selection.

Map ribbon → Select By Attributes.

The dialog requires:

1. Input layer.
2. Selection type (New, Add, Remove, Subset, Switch, Clear).
3. Expression — SQL WHERE clause.

SQL essentials for the exam¶

→ See SQL for GIS for everything you need.

Common exam patterns¶

• "Select all California counties with population over 1 million." → STATE = 'CA' AND POP > 1000000
• "Select all features whose name starts with 'San'." → NAME LIKE 'San%'
• "Select features where median income is missing." → MED_INC IS NULL

→ See Select by Attributes.

3.4 Select by Location¶

A spatial relationship-driven selection.

Map ribbon → Select By Location.

Dialog:

1. Input feature layer (what you want to select from).
2. Relationship.
3. Selecting features (the layer doing the selecting).
4. Search distance (optional, only some relationships).

The 14 relationships you may see¶

Common exam patterns¶

• "Select schools within 1 mile of a park." → Select By Location → Within a distance, 1 mile
• "Select tracts that intersect a flood zone." → Intersect
• "Select counties whose centroid falls in a region polygon." → Have their centroid in
• "Select roads completely inside a study area." → Are completely within

→ See Select by Location, Tutorial: Select by Attributes vs Location.

3.5 Proximity tools¶

Buffer¶

Creates a polygon at a specified distance around input features.

Geoprocessing → Buffer (Analysis Tools).

Parameters:

Near / Generate Near Table¶

• Near adds a NEAR_DIST and NEAR_FID field to the input.
• Generate Near Table outputs a table of every input → near pair.

Common exam patterns¶

• "Find every school's distance to the nearest fire station." → Near or Generate Near Table
• "Buffer rivers by 100 m, but only on the floodplain side." → Side Type
• "Combine all buffers into one shape." → Dissolve Type = ALL

→ See Buffers.

3.6 Overlay tools¶

This is the "which tool?" set of questions on the exam. Memorize this matrix.

Common exam patterns¶

• "Crop streets to a county." → Clip
• "Tag census tracts with the names of the school districts they overlap." → Spatial Join
• "Find areas inside both a flood zone AND a fire risk zone." → Intersect
• "Remove a buffer from a study area." → Erase
• "Merge polygons by attribute." → Dissolve (technically a 'Generalization' tool, but commonly grouped here)

→ See Buffer vs Clip vs Intersect tutorial, Spatial Join.

Quick decision tree¶

flowchart TD
    A[Need to combine layers?] --> B{What do you want?}
    B -->|Crop one layer to another's boundary| C[Clip]
    B -->|Tag features with overlapping attributes| D[Spatial Join]
    B -->|Only the overlapping geometry, all attrs| E[Intersect]
    B -->|Combined extent + attrs of both| F[Union]
    B -->|Input minus another layer| G[Erase]
    B -->|Distance ring around features| H[Buffer]
    B -->|Just count points in polygons| D2[Spatial Join with COUNT]
    B -->|Just measure distance to nearest| I[Near or Generate Near Table]

Domain quick-quiz¶

1. Difference between Clip and Intersect?
2. Which tool tells you the distance from each school to the nearest hospital?
3. How do you select all parcels in California with median home value over $500,000?
4. How would you select counties whose centroid lies within a region polygon?
5. What's the right tool to combine two layers and keep all features even where they don't overlap?

→ Next: Domain 4 — Layouts and Sharing (12%).