Decomposition tree in Power BI - Step-by-Step Guide

Introduction

A decomposition tree helps you explore data by breaking it down into smaller parts. It shows how different categories contribute to a total, making it easier to find patterns or causes in your data.

When you want to see which product categories contribute most to total sales.

When you need to analyze customer complaints by region and then by issue type.

When your manager asks why revenue dropped in a specific quarter.

When you want to explore employee performance by department and then by individual.

When you want to understand which marketing channels drive the most website visits.

Steps

Step 1: Click

- Visualizations pane

The list of available visuals expands

💡 Look for the icon that looks like a branching tree

Step 2: Select

- Decomposition tree visual

A blank decomposition tree visual appears on the report canvas

Step 3: Drag

- Measure or numeric field from Fields pane to 'Analyze' well in the visual

The total value appears at the top of the tree

Step 4: Drag

- Category fields from Fields pane to 'Explain by' well in the visual

These categories become options to break down the total value

Step 5: Click

- Plus (+) icon next to the total or any branch in the decomposition tree

The tree expands showing the breakdown by one of the category fields

Step 6: Select

- Different category from the list that appears after clicking plus (+)

The tree updates to show the breakdown by the selected category

Step 7: Use

- Search box in the decomposition tree

You can quickly find a specific category to expand

Before vs After

Before

The report shows a single total sales number: 100,000

After

The decomposition tree shows total sales 100,000 broken down by Region, then by Product Category, with each branch showing sales amounts

Settings Reference

Explain by fields

📍 Visualizations pane under 'Explain by'

These fields define how the total value is broken down in the tree

Default: None

Analyze field

📍 Visualizations pane under 'Analyze'

This is the main value that the tree breaks down

Default: None

Expand mode

📍 Format pane under 'Expand controls'

Controls if the tree expands only when you click or automatically

Default: Manual

Data labels

📍 Format pane under 'Data labels'

Shows or hides the numeric values on the tree branches

Default: On

Common Mistakes

Not adding any 'Explain by' fields

Without categories to break down by, the tree cannot expand and explore data

Add one or more categorical fields to the 'Explain by' well to enable breakdown

Using a non-numeric field in the 'Analyze' well

The tree needs a number to show totals and breakdowns

Use a numeric measure or field like sales amount or count

Expecting the tree to expand automatically without clicking

By default, expansion is manual to avoid clutter

Click the plus (+) icons to expand branches or change expand mode in settings

Summary

The decomposition tree helps break down a total value into parts using categories.

You add a numeric field to analyze and one or more categories to explain by.

Remember to click plus (+) icons to explore deeper levels unless automatic expand is enabled.