Distribution

Population pyramid

Compares counts or shares for two populations across ordered age groups.

Chart
Distribution
Comparison

What it answers

How do age distributions differ between populations?

Shape: Mirrored age-band bars
What it shows: Age concentration and cohort imbalance.

Example

The question

What is the age and gender make-up of our workforce?

Employees by age band and gender (population pyramid)

Bars touch at the centre, oldest band at the top. Women: 20-29 28; 30-39 41; 40-49 36; 50-59 22; 60+ 8. Men: 20-29 34; 30-39 46; 40-49 30; 50-59 25; 60+ 12.

Illustrative data. It belongs to no company.

When to use it

Use it when

Two-population demographic structures.

Avoid it when

Different age bands or incompatible percentage denominators.

How to read it

Read age bands in order and compare left/right lengths at the same age.

Note

Use consistent age bands and percentage denominators.

The data you need

Layout: Long table
Fields: AgeBand: ordered text; Population: text; Count or Share: nonnegative number
One row is: One population and age-band amount. What is the grain?
Rules: Use consistent age boundaries and a shared age order. Mirror one group only in the chart, not by changing raw counts.
Optional: If shares are used, define within-group versus total-population denominators.
Preparation: Validate the input grain and missing values. Use consistent age boundaries and a shared age order. Mirror one group only in the chart, not by changing raw counts.
Units: Counts or percentages by age band. Define whether percentages divide by each population total or a combined population.

A long table: one row per observation, few columns. New data adds rows.

Worked example

Age 0-9: A120, B115; age 10-19: A130, B125. A is 5 higher in each band; totals alone do not establish age-adjusted differences.

AgeBand	Population	Count
0-9	A	120
0-9	B	115
10-19	A	130
10-19	B	125

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