Make the First Choice
| Question or detail | Chart | What to check |
|---|---|---|
| How does a rate vary across regions? | Choropleth Map | A region identifier and comparable rate or percentage for each area. |
| Where are larger site-level values located? | Bubble Map | Latitude, longitude, and a nonnegative value at each location. |
| Which place has the highest value? | Bar Chart | Comparable values and a deliberate ordering of place names. |
WORKED EXAMPLE / ILLUSTRATIVE DATA
Separate Regional Coverage From Site Activity
Suppose a fictional service measures regional coverage and requests at city sites during the same month. These are different measures at different geographic levels. Do not color a whole country with its city count or place a country rate at an arbitrary city.
| Geographic Unit | Measure | Value | Suitable Map |
|---|---|---|---|
| Canada | Regional Coverage (%) | 84 | Choropleth Map |
| Brazil | Regional Coverage (%) | 56 | Choropleth Map |
| New York Site | Requests | 120 | Bubble Map |
| Nairobi Site | Requests | 30 | Bubble Map |
The two city values differ by a factor of four. A proportional Bubble Map gives the larger circle four times the area and twice the radius. Coverage percentages use a separate regional color scale.
Match the Geography to the Measure
Regional totals often reflect population or the number of eligible customers. Use a justified denominator when comparing rates, and label its population and time period. ChartTypes expects the final value; it does not calculate regional rates.
A coordinate is a point, not a geographic boundary. The location editor does not infer coordinates from names. Keep latitude and longitude in the correct columns and confirm that the supplied location represents the measurement.
Distinguish Missing Data and Zero
The Choropleth Map leaves absent regions gray and colors supplied zeros light blue. Missing data does not mean no activity. Bubble Map keeps zeros in the data but gives them no visible circle; its table remains essential for distinguishing zero-valued locations from absent ones.
Read Size and Color Carefully
Circle area is proportional to value, so radius grows with the square root of value. Larger circles can hide smaller or coincident locations. The examples draw larger ones first without shifting coordinates.
Both examples scale to the largest supplied value. Editing that maximum can change every mark. For multiple maps or time comparisons, use a common color domain or circle-size scale and a clear legend.
Recognize Projection and Boundary Limits
The examples share an equirectangular world view. It distorts geographic area and distance, especially near the poles. Large regions also occupy more visual space in a Choropleth Map regardless of their value.
The bundled boundaries are simplified for an overview and omit some small territories. Their region codes are specific to the map dataset. Use the dropdown identifiers for regional matching; do not assume every code is an ISO identifier. State-level boundaries and geographic uploads are outside these examples.
Before You Publish
- Confirm that location helps answer the question.
- Match the geographic unit, time period, and denominator across values.
- Keep missing values distinct from zero.
- Use circle area, rather than radius, to represent value.
- Include a table for exact values and overlapping locations.
Explore Working Examples
Open a chart to inspect its sample data and compare code in six libraries.