Area charts in Tableau - Dashboard Guide

Dashboard Mode - Area charts

Dashboard Goal

Understand how sales change over months and compare product categories using area charts.

Sample Data

Month	Category	Sales
Jan	Furniture	200
Jan	Technology	300
Feb	Furniture	250
Feb	Technology	350
Mar	Furniture	300
Mar	Technology	400
Apr	Furniture	280
Apr	Technology	420

Dashboard Components

• KPI Card: Total Sales
  Formula: SUM([Sales])
  Result: 2500
• Area Chart 1: Monthly Sales Trend
  Details: Shows total sales per month.
  Calculation: Aggregate sales by month using SUM([Sales]).
  Chart type: Area chart with Month on X-axis and Sales on Y-axis.
• Area Chart 2: Sales by Category Over Time
  Details: Compares sales trends for Furniture and Technology.
  Calculation: Sales by Month and Category using SUM([Sales]).
  Chart type: Stacked area chart with Month on X-axis, Sales on Y-axis, and Category as color.
• Data Table: Sales Details
  Shows raw data for reference with columns Month, Category, Sales.

Dashboard Layout

+----------------------+---------------------------+
|      KPI Card        |      Area Chart 1          |
|   Total Sales: 2500  |   Monthly Sales Trend     |
+----------------------+---------------------------+
|                  Area Chart 2 (Stacked)             |
|               Sales by Category Over Time           |
+-----------------------------------------------------+
|                     Data Table                       |
+-----------------------------------------------------+

Interactivity

A filter for Category allows users to select one or both categories. When a category is selected, Area Chart 2 and the Data Table update to show only the selected category's data. The KPI Card and Area Chart 1 update to reflect total sales for the filtered data.

A filter for Month lets users focus on specific months. All components update accordingly to show data only for the selected months.

Self Check

If you add a filter to select only the Furniture category, which components update and what changes occur?

• KPI Card: Total Sales changes to 1030 (200+250+300+280).
• Area Chart 1: Shows monthly sales trend only for Furniture.
• Area Chart 2: Displays only the Furniture area, no Technology.
• Data Table: Shows only rows where Category is Furniture.

Key Result

Dashboard showing total sales and monthly sales trends by category using area charts with interactive filters.

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