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.

Practice

1. Why is combining different chart types in Tableau useful for storytelling?

easy

A. It automatically cleans the data for better accuracy.

B. It reduces the amount of data needed for analysis.

C. It shows multiple data perspectives in one view, making insights clearer.

D. It hides less important data to simplify the dashboard.

Solution

1. Step 1: Understand the purpose of combining charts

   Combining charts allows showing different aspects of data together, like trends and totals.

2. Step 2: Recognize how this helps storytelling

   Showing multiple perspectives in one view helps users understand the full story behind the data.

3. Final Answer:

   It shows multiple data perspectives in one view, making insights clearer. -> Option C

4. Quick Check:

   Combining charts = richer story [OK]

Hint: Think: multiple views = clearer story [OK]

Common Mistakes:

• Confusing data cleaning with visualization
• Assuming combining charts hides data
• Believing it reduces data volume

2. Which Tableau feature allows you to layer two different chart types on the same axis?

easy

A. Filter Action

B. Data Blending

C. Calculated Field

D. Dual Axis

Solution

1. Step 1: Identify the feature for layering charts

   Dual Axis lets you put two charts on the same axis to compare them directly.

2. Step 2: Confirm other options don't layer charts

   Data Blending combines data sources, Calculated Field creates new data, Filter Action filters views.

3. Final Answer:

   Dual Axis -> Option D

4. Quick Check:

   Layer charts = Dual Axis [OK]

Hint: Layer charts? Use Dual Axis [OK]

Common Mistakes:

• Confusing data blending with layering charts
• Thinking calculated fields layer charts
• Mixing filter actions with layering

3. Given a Tableau dashboard with a bar chart showing sales and a line chart showing profit on a dual axis, what is the main benefit?

medium

A. It hides the profit data to focus on sales only.

B. It allows comparing sales and profit trends on the same timeline.

C. It duplicates the sales data for emphasis.

D. It automatically changes the data source.

Solution

1. Step 1: Understand dual axis with bar and line charts

   Dual axis lets you see two measures (sales and profit) together on the same timeline.

2. Step 2: Recognize the benefit of comparing trends

   This helps spot relationships or differences between sales and profit over time.

3. Final Answer:

   It allows comparing sales and profit trends on the same timeline. -> Option B

4. Quick Check:

   Dual axis = compare trends [OK]

Hint: Dual axis shows two trends together [OK]

Common Mistakes:

• Thinking dual axis hides data
• Assuming data duplication occurs
• Believing data source changes automatically

4. You created a dual axis chart in Tableau but the two charts do not align properly. What is the most likely cause?

medium

A. The axes scales are not synchronized.

B. The data source is missing.

C. The filter is applied incorrectly.

D. The dashboard size is too small.

Solution

1. Step 1: Identify why dual axis charts misalign

   If axes scales differ, charts won't line up properly on the same axis.

2. Step 2: Check other options for relevance

   Missing data source or filter issues cause errors, not misalignment; dashboard size affects layout but not axis alignment.

3. Final Answer:

   The axes scales are not synchronized. -> Option A

4. Quick Check:

   Misaligned dual axis = unsynced scales [OK]

Hint: Sync axes scales to align charts [OK]

Common Mistakes:

• Blaming data source for alignment
• Confusing filter issues with axis scale
• Ignoring axis synchronization

5. You want to create a dashboard showing monthly sales as bars and cumulative sales as a line on the same chart. Which steps should you follow in Tableau to tell this richer story?

hard

A. Create bar chart for monthly sales, create line chart for cumulative sales, use Dual Axis, synchronize axes, and format clearly.

B. Create two separate charts and place them side by side without linking axes.

C. Use a pie chart for monthly sales and a scatter plot for cumulative sales on different dashboards.

D. Create a single bar chart and add cumulative sales as a tooltip.

Solution

1. Step 1: Build individual charts for monthly and cumulative sales

   Create a bar chart for monthly sales and a line chart for cumulative sales to show both details.

2. Step 2: Combine charts using Dual Axis and synchronize axes

   Use Dual Axis to layer charts on the same timeline and synchronize axes for alignment.

3. Step 3: Format charts clearly for easy understanding

   Adjust colors, labels, and legends to keep the visualization clear and accessible.

4. Final Answer:

   Create bar chart for monthly sales, create line chart for cumulative sales, use Dual Axis, synchronize axes, and format clearly. -> Option A

5. Quick Check:

   Dual Axis + sync axes + clear format = richer story [OK]

Hint: Dual Axis + sync axes + clear format [OK]

Common Mistakes:

• Placing charts separately without linking
• Using unrelated chart types for this story
• Relying on tooltips instead of combined view