Part of a whole
100% stacked column chart
Normalises each column to 100% to compare composition across categories or periods.
- Chart
- Composition
- Trend over time
What it answers
How does composition change over time?
- Shape
- Equal-height segmented columns
- What it shows
- Share shifts independent of changing totals.
Example
The question
How has the mix of contract types changed since 2022?
Staff by contract type, share of headcount
Illustrative data. It belongs to no company.
When to use it
Use it when
Comparing shares across periods.
Avoid it when
When readers need absolute growth or total amounts.
How to read it
Read each column as 100% and compare segment percentages over periods.
Note
Absolute totals are hidden.
The data you need
- Layout
- Long table
- Fields
- Category or ordered position: text/date; Series: text; Value: number
- One row is
- One series value within one category or position. What is the grain?
- Rules
- Use one value per category-series pair after aggregation. Define category and series order.
- Optional
- Wide alternative: Category,North,South with one row per category.
- Preparation
- Aggregate components per period/category and normalise each column to 100%. Preserve the unnormalised totals.
- Units
- Percent of each period/category column total. Counts behind different columns can differ.
Worked example
Data Jan=(30,45), Feb=(34,40). Normalise columns. The first share rises from 40% to about 45.9%, despite a smaller total.
| Category | Series | Value |
|---|---|---|
| A | North | 30 |
| A | South | 45 |
| B | North | 34 |
| B | South | 40 |