Dual axis charts in Tableau - Real Business Scenario

Scenario Mode

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

📋 Request: Your manager wants to see how monthly sales revenue and the number of units sold trend together over the past year to understand their relationship.

📊 Data: You have monthly sales data including 'Month', 'Sales Revenue' (in dollars), and 'Units Sold'.

🎯 Deliverable: Create a dual axis line chart in Tableau showing both Sales Revenue and Units Sold over the months of the year.

Sample Data

Month	Sales Revenue	Units Sold
Jan	12000	300
Feb	15000	350
Mar	13000	320
Apr	17000	400
May	16000	380
Jun	18000	420
Jul	20000	450
Aug	21000	460
Sep	19000	430
Oct	22000	480
Nov	23000	500
Dec	25000	520

1

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

No formula needed; just connect and import the data.

Expected Result

Data with columns Month, Sales Revenue, and Units Sold is available in Tableau.

2

Step 2: Drag 'Month' to the Columns shelf to create the timeline.

Columns: Month

Expected Result

Months appear along the horizontal axis.

3

Step 3: Drag 'Sales Revenue' to the Rows shelf to create the first line chart.

Rows: SUM(Sales Revenue)

Expected Result

A line chart showing total sales revenue per month appears.

4

Step 4: Drag 'Units Sold' to the Rows shelf next to Sales Revenue to add the second measure.

Rows: SUM(Units Sold)

Expected Result

Two separate line charts stacked vertically appear.

5

Step 5: Right-click on the second axis (Units Sold) and select 'Dual Axis' to overlay the two charts.

Right-click SUM(Units Sold) axis > Dual Axis

Expected Result

Sales Revenue and Units Sold lines share the same horizontal axis but have separate vertical axes.

6

Step 6: Format the chart: assign different colors to each line, add axis titles, and add a chart title 'Monthly Sales Revenue and Units Sold'.

Use Color shelf for lines; edit axis titles and chart title in the worksheet.

Expected Result

Clear, colorful dual axis line chart with proper labels and title.

Final Result

Month ->

| 25000 +---------------------------------------------------+ 520
|       |\                                                  /|    
| 20000 + \                                                / + 450
|       |  \                                              /  |    
| 15000 +   \                                            /   + 350
|       |    \                                          /    |    
| 10000 +     \                                        /     + 300
|       |      \                                      /      |    
|  5000 +       \                                    /       +    
|       |        \                                  /        |    
|     0 +---------\--------------------------------/---------+  0
|          Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Legend:
- Solid line: Sales Revenue
- Dashed line: Units Sold

✓Sales Revenue and Units Sold generally increase together over the year.

✓There is a steady growth trend from January to December.

✓The dual axis chart helps see how revenue and units sold relate month by month.

Bonus Challenge

Add a third measure, 'Profit Margin', as a dual axis chart with a different chart type (e.g., bars) on the same timeline.

Show Hint

Use the 'Measure Names' and 'Measure Values' fields in Tableau to combine multiple measures and change the mark type for each measure.

Practice

1. What is the main purpose of a dual axis chart in Tableau?

easy

A. To filter data based on two conditions

B. To create two separate charts side by side

C. To compare two different measures on the same graph using two axes

D. To combine two dimensions into one axis

Solution

1. Step 1: Understand what dual axis means

   A dual axis chart shows two measures on one graph but with two separate axes, usually one on the left and one on the right.

2. Step 2: Compare options with this definition

   Only To compare two different measures on the same graph using two axes describes comparing two measures on the same graph using two axes, which matches the definition.

3. Final Answer:

   To compare two different measures on the same graph using two axes -> Option C

4. Quick Check:

   Dual axis = compare two measures on one graph [OK]

Hint: Dual axis means two measures, two axes on one chart [OK]

Common Mistakes:

• Thinking dual axis creates two separate charts
• Confusing dual axis with filtering
• Mixing up dimensions and measures

2. Which of the following is the correct way to create a dual axis chart in Tableau?

easy

A. Drag one measure to Filters and one measure to Tooltip, then select 'Dual Axis'

B. Drag one measure to Columns and one dimension to Rows, then select 'Dual Axis'

C. Drag two dimensions to Rows shelf and select 'Dual Axis'

D. Drag two measures to Rows shelf, right-click second measure, and select 'Dual Axis'

Solution

1. Step 1: Recall the dual axis creation steps

   To create a dual axis chart, you drag two measures to the Rows or Columns shelf, then right-click the second measure and choose 'Dual Axis'.

2. Step 2: Check each option

   Drag two measures to Rows shelf, right-click second measure, and select 'Dual Axis' matches the correct method. The other options misuse dimensions or shelves and do not create dual axis charts.

3. Final Answer:

   Drag two measures to Rows shelf, right-click second measure, and select 'Dual Axis' -> Option D

4. Quick Check:

   Drag two measures + Dual Axis = correct method [OK]

Hint: Drag two measures, right-click second, pick 'Dual Axis' [OK]

Common Mistakes:

• Using dimensions instead of measures for dual axis
• Trying to dual axis with filters or tooltips
• Not right-clicking the second measure

3. Given a dual axis chart with Sales on the left axis and Profit on the right axis, what happens if you do NOT synchronize the axes?

medium

A. The chart will show an error and not display

B. The two measures may appear on different scales, making comparison misleading

C. Both axes will automatically use the same scale

D. The marks for both measures will merge into one

Solution

1. Step 1: Understand axis synchronization

   Synchronizing axes means making both axes use the same scale so the measures can be compared fairly.

2. Step 2: Consider what happens without synchronization

   Without synchronization, each axis uses its own scale, so the measures may look very different even if values are similar, causing misleading visuals.

3. Final Answer:

   The two measures may appear on different scales, making comparison misleading -> Option B

4. Quick Check:

   Unsynchronized axes = different scales, misleading comparison [OK]

Hint: Unsync axes = different scales, hard to compare [OK]

Common Mistakes:

• Assuming Tableau auto-syncs axes always
• Thinking chart shows error without sync
• Believing marks merge automatically

4. You created a dual axis chart but the marks for the second measure do not appear. What is the most likely cause?

medium

A. You did not assign a mark type to the second axis

B. You forgot to synchronize the axes

C. You dragged a dimension instead of a measure for the second axis

D. You did not drag the second measure to the Tooltip shelf

Solution

1. Step 1: Check mark types for dual axis

   Each axis in a dual axis chart needs a mark type (like bar, line) assigned to show its data points.

2. Step 2: Identify why marks might be missing

   If the second axis has no mark type assigned, its marks won't display even if data is present.

3. Final Answer:

   You did not assign a mark type to the second axis -> Option A

4. Quick Check:

   No mark type = no marks shown [OK]

Hint: Assign mark type to each axis to show marks [OK]

Common Mistakes:

• Confusing axis sync with mark visibility
• Dragging dimensions instead of measures
• Thinking Tooltip shelf controls marks

5. You want to create a dual axis chart comparing monthly Sales (as bars) and Profit Ratio (as a line) over a year. Which steps correctly achieve this?

hard

A. Drag Sales and Profit Ratio to Rows, right-click Profit Ratio and select 'Dual Axis', then set Sales marks to Bar and Profit Ratio marks to Line

B. Drag Sales to Columns and Profit Ratio to Rows, then combine using 'Dual Axis', set both marks to Bar

C. Drag Sales and Profit Ratio to Rows, synchronize axes, then set both marks to Line

D. Drag Sales to Rows, Profit Ratio to Tooltip, then select 'Dual Axis' and set marks to Bar and Line

Solution

1. Step 1: Place both measures on Rows shelf

   Drag Sales and Profit Ratio to Rows to prepare for dual axis.

2. Step 2: Create dual axis and assign mark types

   Right-click Profit Ratio and select 'Dual Axis' to combine. Then set Sales marks to Bar and Profit Ratio marks to Line for clarity.

3. Final Answer:

   Drag Sales and Profit Ratio to Rows, right-click Profit Ratio and select 'Dual Axis', then set Sales marks to Bar and Profit Ratio marks to Line -> Option A

4. Quick Check:

   Dual axis + different marks = clear comparison [OK]

Hint: Dual axis + set different marks for clarity [OK]

Common Mistakes:

• Not setting different mark types for clarity
• Dragging measures to different shelves incorrectly
• Using Tooltip shelf instead of Rows or Columns