Why combining chart types tells richer stories in Tableau - Business Case Study

Scenario Mode

👤 Your Role: You are a sales analyst at a retail company.

📋 Request: Your manager wants a report that shows monthly sales performance and the proportion of sales by product category together, to better understand trends and category contributions.

📊 Data: You have monthly sales data with columns: Month, Sales Amount, and Product Category.

🎯 Deliverable: Create a combined chart in Tableau that shows monthly total sales as a line chart and sales proportion by product category as stacked bars for each month.

Sample Data

Month	Product Category	Sales Amount
Jan	Electronics	5000
Jan	Clothing	3000
Jan	Home	2000
Feb	Electronics	6000
Feb	Clothing	3500
Feb	Home	2500
Mar	Electronics	5500
Mar	Clothing	4000
Mar	Home	3000

1

Step 1: Connect your data source in Tableau and load the sales data.

No formula needed; just connect and load the data.

Expected Result

Data with columns Month, Product Category, and Sales Amount is available in Tableau.

2

Step 2: Create a calculated field for Total Sales per Month.

Create calculated field named 'Total Sales' with formula: SUM([Sales Amount])

Expected Result

Total Sales sums sales amounts for each month.

3

Step 3: Build a line chart showing Total Sales over Months.

Drag 'Month' to Columns, 'Total Sales' to Rows, change mark type to Line.

Expected Result

Line chart showing total sales trend by month.

4

Step 4: Create a stacked bar chart showing Sales Amount by Product Category for each Month.

Drag 'Month' to Columns, 'Sales Amount' to Rows, 'Product Category' to Color, mark type Bar.

Expected Result

Stacked bars showing sales distribution by category per month.

5

Step 5: Combine the line chart and stacked bar chart into a dual-axis chart.

Right-click on second 'Sales Amount' axis, select 'Dual Axis', synchronize axes, set line chart on top, stacked bars below.

Expected Result

Combined chart with line showing total sales trend and stacked bars showing category proportions.

6

Step 6: Format the combined chart for clarity: add axis titles, legend, and tooltips.

Add axis titles 'Month' and 'Sales Amount', ensure legend shows product categories, enable tooltips.

Expected Result

Clear, readable combined chart that tells a richer story.

Final Result

Month  | Jan       Feb       Mar
-------------------------------------
Sales  | 10000     12000     12500
        |  _______   _______   _______
        | |       | |       | |       |
        | |  *    | |   *   | |   *   |  * = Total Sales Line
        | |_______| |_______| |_______|
        |  | | |    | | | |    | | | |
        |  E C H    E C H    E C H
        |  (Stacked bars by Electronics, Clothing, Home)

Bonus Challenge

Add a filter to the combined chart to allow viewing sales by specific product categories dynamically.

Show Hint

Use Tableau's filter shelf to add 'Product Category' filter and show filter control on the dashboard.