Area charts in Tableau - Cell-by-Cell Formula Trace

Sample Data

Monthly sales data for 5 months

Cell	Value
A1	Month
B1	Sales
A2	Jan
B2	100
A3	Feb
B3	150
A4	Mar
B4	130
A5	Apr
B5	170
A6	May
B6	160

Formula Trace

SUM([Sales]) OVER (ORDER BY [Month] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

Step 1: Sales values by month: Jan=100, Feb=150, Mar=130, Apr=170, May=160

Step 2: Calculate running total for Jan: SUM of sales from Jan to Jan

Step 3: Calculate running total for Feb: SUM of sales from Jan to Feb

Step 4: Calculate running total for Mar: SUM of sales from Jan to Mar

Step 5: Calculate running total for Apr: SUM of sales from Jan to Apr

Step 6: Calculate running total for May: SUM of sales from Jan to May

Cell Reference Map

    A       B
1 Month   Sales
2 Jan     100
3 Feb     150
4 Mar     130
5 Apr     170
6 May     160

Formula uses column B (Sales) values ordered by column A (Month).

The formula references the Sales column (B2:B6) ordered by Month (A2:A6) to calculate running totals.

Result

    A       B       C
1 Month   Sales   Running Total
2 Jan     100     100
3 Feb     150     250
4 Mar     130     380
5 Apr     170     550
6 May     160     710

The Running Total column shows cumulative sales by month. This data is used to create the area chart, where the area under the line grows with each month.

Sheet Trace Quiz - 3 Questions

What is the running total sales value for March?

A 130

B 380

C 250

D 550

Key Result

Running total calculation sums values from the start up to the current row ordered by a dimension.

Practice

1. What is the main purpose of an area chart in Tableau?

easy

A. To show trends and the total amount by filling the area under a line

B. To display individual data points without connecting lines

C. To compare categories using bars of different lengths

D. To show relationships between two numerical variables using dots

Solution

1. Step 1: Understand area chart basics

   An area chart fills the space under a line to emphasize the magnitude of values over time or categories.

2. Step 2: Compare with other chart types

   Unlike scatter plots or bar charts, area charts focus on trends and totals by shading the area below the line.

3. Final Answer:

   To show trends and the total amount by filling the area under a line -> Option A

4. Quick Check:

   Area chart = filled trend line [OK]

Hint: Area charts fill space under lines to show totals [OK]

Common Mistakes:

• Confusing area charts with scatter plots
• Thinking area charts only show individual points
• Using area charts to compare unrelated categories

2. Which of the following is the correct way to create an area chart in Tableau?

easy

A. Drag a measure to Filters, a dimension to Pages, then select 'Line' mark type

B. Drag a dimension to Rows, a measure to Columns, then select 'Circle' mark type

C. Drag two measures to Rows and Columns, then select 'Bar' mark type

D. Drag a measure to Rows, a dimension to Columns, then select 'Area' mark type

Solution

1. Step 1: Identify correct field placement

   For area charts, a measure (numeric data) goes on Rows and a dimension (categories or time) on Columns.

2. Step 2: Choose the correct mark type

   After placing fields, select the 'Area' mark type to fill the area under the line.

3. Final Answer:

   Drag a measure to Rows, a dimension to Columns, then select 'Area' mark type -> Option D

4. Quick Check:

   Measure + Dimension + Area mark = Area chart [OK]

Hint: Measure on Rows + Dimension on Columns + Area mark [OK]

Common Mistakes:

• Using Circle or Bar mark types instead of Area
• Placing dimensions on Rows instead of Columns
• Not selecting the Area mark type after placing fields

3. Given a dataset with sales over months and product categories, what will happen if you create an area chart with Month on Columns, SUM(Sales) on Rows, and Category on Color?

medium

A. The chart will show stacked colored areas for each category over months

B. The chart will show separate lines without filled areas

C. The chart will show a single color area for total sales only

D. The chart will produce an error because color cannot be used here

Solution

1. Step 1: Understand field roles in area chart

   Month on Columns creates the timeline, SUM(Sales) on Rows shows total sales, and Category on Color splits the area by product categories.

2. Step 2: Visualize the result

   Each category's sales area stacks on top of others, showing contribution per month with different colors.

3. Final Answer:

   The chart will show stacked colored areas for each category over months -> Option A

4. Quick Check:

   Color by category = stacked colored areas [OK]

Hint: Color splits area into stacked parts by group [OK]

Common Mistakes:

• Expecting separate lines instead of stacked areas
• Thinking color only changes line color, not area
• Assuming color cannot be used with area charts

4. You created an area chart but the areas overlap and colors are not stacked. What is the most likely cause?

medium

A. The color field is missing or not assigned

B. The dimension is on Rows instead of Columns

C. The mark type is set to 'Line' instead of 'Area'

D. The measure is aggregated incorrectly

Solution

1. Step 1: Check the mark type

   If the mark type is 'Line', the chart shows lines without filled areas, causing overlap and no stacking.

2. Step 2: Confirm correct mark type for area chart

   Changing the mark type to 'Area' fills the space under the lines and stacks colors properly.

3. Final Answer:

   The mark type is set to 'Line' instead of 'Area' -> Option C

4. Quick Check:

   Line mark = no filled areas [OK]

Hint: Use 'Area' mark type to avoid overlapping lines [OK]

Common Mistakes:

• Ignoring mark type and blaming data placement
• Not assigning color field for stacking
• Misunderstanding aggregation effects on area charts

5. You want to compare monthly sales trends for two regions using an area chart in Tableau. Which approach best highlights differences clearly?

hard

A. Place Region on Columns, Month on Rows, and SUM(Sales) on Size with 'Circle' mark type

B. Place Month on Columns, SUM(Sales) on Rows, and Region on Color with 'Area' mark type

C. Place Month on Rows, Region on Columns, and SUM(Sales) on Rows with 'Bar' mark type

D. Place SUM(Sales) on Columns, Month on Rows, and Region on Detail with 'Line' mark type

Solution

1. Step 1: Set timeline and measure correctly

   Month on Columns creates the timeline axis, SUM(Sales) on Rows shows sales values.

2. Step 2: Use Region on Color with Area mark

   Assigning Region to Color splits the area chart into colored stacked or overlapping areas per region, making differences visible.

3. Final Answer:

   Place Month on Columns, SUM(Sales) on Rows, and Region on Color with 'Area' mark type -> Option B

4. Quick Check:

   Color by region + Area mark = clear comparison [OK]

Hint: Use color for groups and area mark for trends [OK]

Common Mistakes:

• Using Circle or Bar marks instead of Area
• Placing Region on Columns instead of Color
• Not using Month on Columns for timeline