Part of a whole
Unit chart / unit grid
Represents individual units or equal-sized bundles with repeated marks.
- Chart
- Composition
- Magnitude
What it answers
How are individual units allocated?
- Shape
- Grid of one-unit marks
- What it shows
- Counts, composition and individual categories.
Example
The question
How are our 340 employees spread across departments?
Employees by department, one dot = 5 people
Illustrative data. It belongs to no company.
When to use it
Use it when
Showing discrete membership or allocation.
Avoid it when
Very large populations without aggregation or when marks suggest false individuality.
How to read it
Read one mark as one unit or a stated bundle and count by group.
Note
State whether each mark is one individual or an aggregated bundle.
The data you need
- Layout
- Unit records or category-count table
- Fields
- UnitID: text; Category: text; or Category and Count
- One row is
- One unit with its category, or one aggregated category count. What is the grain?
- Rules
- Use unique unit IDs for unit-level data. For counts, define units per rendered mark and rounding.
- Optional
- Alternative: Category,Count with whole-number counts.
- Preparation
- Check nonnegative components, reconcile the represented whole and aggregate duplicate categories. Define whether records are counts or already normalised shares.
- Units
- Show counts or shares of a named whole. Share = component / relevant total; name that total and the population/period it covers.
Worked example
Records U1=A, U2=A, U3=B give three marks: two A and oneB. A represents 2/3 of these units.
| UnitID | Category |
|---|---|
| U1 | A |
| U2 | A |
| U3 | B |