Distribution analysis (box plots) in Tableau - Step-by-Step Guide

Introduction

Box plots help you see how data spreads out and where most values lie. They show the middle, spread, and any unusual points in your data. This helps you understand patterns and spot outliers easily.

When you want to compare sales spread across different regions to see which region has more consistent sales.

When you need to check the distribution of customer ages to understand the main age groups.

When analyzing delivery times to find if some orders take much longer than usual.

When you want to see the range and median of product prices in different categories.

When you want to detect outliers in employee performance scores.

Steps

Step 1: Open your Tableau workbook

- Tableau Desktop start screen or existing workbook

Your data source and sheets are visible

💡 Make sure your data includes the measure you want to analyze

Step 2: Drag the dimension you want to group by (e.g., Region) to Columns

- Data pane to Columns shelf

Columns shelf shows the selected dimension, and the view updates with headers for each group

Step 3: Drag the measure you want to analyze (e.g., Sales) to Rows

- Data pane to Rows shelf

Rows shelf shows the measure, and a vertical axis appears with data points

Step 4: Click on the Show Me panel and select the Box-and-Whisker Plot icon

- Show Me panel on the right side

Tableau changes the chart to a box plot showing distribution for each group

Step 5: Adjust the axes or add filters if needed

- Axes or Filters shelf

The box plot updates to reflect any changes or filters applied

Step 6: Add tooltips or labels for clarity

- Marks card → Tooltip or Label

Hovering over or viewing the plot shows detailed values like median and quartiles

Before vs After

Before

View shows a simple bar chart of total sales by region with no detail on spread

After

View shows box plots for each region displaying median, quartiles, and outliers of sales

Settings Reference

Box Plot Type

📍 Show Me panel

Select the box plot visualization type to analyze distribution

Default: None (choose manually)

Filters

📍 Filters shelf

Limit data shown in the box plot to focus on specific subsets

Default: No filters applied

Tooltip

📍 Marks card → Tooltip

Display detailed statistics when hovering over parts of the box plot

Default: Show default tooltip

Axis Range

📍 Axis options (right-click axis)

Control the scale of the axis to better compare distributions

Default: Automatic

Common Mistakes

Using a continuous dimension on Columns instead of a discrete dimension

Box plots require grouping by categories to show distribution per group

Use a discrete dimension like Region or Category on Columns to group data

Dragging a measure to Columns instead of Rows

This can flip the box plot orientation and confuse interpretation

Place the measure on Rows and the grouping dimension on Columns for standard vertical box plots

Not selecting the box plot type from Show Me

Tableau defaults to other chart types that do not show distribution

Always select the Box-and-Whisker Plot icon in Show Me after placing fields

Summary

Box plots in Tableau show how data spreads and highlight medians and outliers.

Use discrete dimensions to group data and measures to analyze distribution.

Remember to select the box plot type from the Show Me panel for correct visualization.