What is a Slope Chart?

Slope charts (or graphs) are essentially a streamlined version of a line chart. Meaning that a slope chart shows the developments between two points. The slope connecting the two points in the graph is linear, with 1 out of 3 directions: upwards, downwards or same level. These charts are a good solution to communicate a story taking place in two different timelines. They look something like this:

Slope Chart Final

Why Slope Charts?

There are several reasons why you might want to use a slope chart in your views, because:

  • It is one of the best ways to visualize the trend between multiple instances over two periods of time.
  • It is less cluttered than line charts.
  • The story the data is trying to convey is easily understood.
  • It is good for showing crucial aspects of business (changes in sales, costs prices,…).
  • Details are not necessary to show.

How to make a Slope Chart in Tableau

To make a slope chart, make sure you have two different instances that you can compare your data with, such as a time interval, countries, or essentially two different categories. In this example, I will use two different years to compare the most popular names in the United States.

In my dataset, I have:

  • Name: The baby name
  • Count: the count for how many times that name has been used
  • Birth Year: the year ranging from 2011 to 2014

Creating the Chart

First, I will drag the “Birth Year” field into columns and have the “SUM(Count)” on the rows. Make sure you have the year field on discrete.

Slope Chart Step 1

Remember that slope charts work for visualizing the trends between two categories. Therefore I should have a filter on year, only showing two, such as 2011 and 2013, as shown below:

Slope Chart Step 2

The next step is to label the individual names on the view. For this, I will drag the “Name” field into the Label marks card:

Slope Chart Step 3

After this step, it is crucial to add a rank table calculation to the “SUM(Count)” and compute using “Name“.

  1. Right-click “SUM(Count)” pill on columns > Quick Table Calculation > Rank
  2. Right-click “SUM(Count)” pill on columns > Compute Using > “Name

This will result in me being able to visualize the the difference in the number of times a name has occurred in 2011 and 2013. Here is how it looks:

Slope Chart Step 4

However, this chart looks really cluttered. It would be best practice to filter the names. For the next step, I will add a filter to “SUM(Count)” that ranges from 1 to 10. That way I can see the top 10 names used in the years 2011 and 2013:

  1. (CTRL + drag) the “SUM(Count)” pill to the Filters shelf > Select “Range of Values” > add “1” on the left text box and 10on the right text box.
  2. Press OK.
  3. Right-click the “Rank of Count” axis > Select Edit Axis > Check “Reversed” box under Scale.

Without reversing the axis, we would see a descending order. And in normal ranking situations, number 1 is generally displayed at the top.

Slope Chart Step 5

Cleaning the Chart

This is pretty much all the steps you need to take to make a slope chart in Tableau. However, the steps after this include cleaning of the view which I think is quite important as well.

Steps for cleaning the view:

  1. Edit Labels: Right-click and drag the “SUM(Count)” pill to the Label Marks card > Click the Label card and press “…” next to “Text” > Format the text to be: “<Rank of SUM(Count)> <Name>
  2. Align View: Click Label card and select “Line Ends” under Marks to Label heading > While on Label, select “Middle” under Alignment.
  3. Hide Axis and Grid Lines: Right-Click “Rank of Count” Axis and un-check “Show Header” > Right-click the view > Select “Format” > Navigate to “Lines” tab > Select “Rows” > Choose “None” for the Grid Lines.

Once you complete these steps, the view looks like this:

Slope Chart Step 6

From this view, I can observe the changes that occurred in ranking of the most popular baby names between 2011 to 2013 with a glance. “Jayden” seems to be the most popular name across the two timelines meanwhile the name “Matthew” has dropped significantly in popularity from 4th place to 10th.

In this blog post, I have described what a slope chart is and why and in what contexts it can be used. I also showed you an example on how to create one yourself.

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