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How to make
Small Multiples Slope Graphs
in Power BI

Before jumping into learning how to build them, let’s briefly review what slope graphs and small multiples are, separately.

A slope graph is a graphic method that:

      1. Consists of using the same units of measurement and seeing the magnitude of change by looking at the steepness of a line’s slope located on an ordinal or interval scale. The steeper the slope, the higher the change.
      2. Additionally, it helps in discerning how different line slopes compare to others at-a-glance, along with displaying the hierarchy of the lines. Lines with greater values on top, and those with low values on bottom.
      3. Finally, it assists in signaling any notable deviation(s) from the general trend or pattern of all the lines.

Now, small multiples are a graphic method that:

      1. Consists of using the same units of measurement with a series of similar graphs arranged in a grid using the same scale and axes, which allows the viewer to easily compare the graphs in the grid displayed.
      2. Additionally, due to its constancy of design it helps the viewer put greater emphasis on the multivariate perspective of the information displayed so comparisons can be made at-a-glance without interruption.
      3. Finally, it can display the changes in the data by both isolating the details and placing them in context along with communicating different views all-at-once.

Let’s see some examples of slope graphs and small multiples, separately and combined in the following video (part 1 of 3)

—— place video 1 here —–

In summary, slope graphs display magnitudes of change, and can hierarchically rank those changes, along with potentially signaling outlier slopes. On the other hand, small multiples are economical because once the viewer can comprehend the design of one of the multiples then it has inmediate access to the information of the other multiples and can focus on changes in the data rather than on changes in graphical design of the grid of the small multiples.

Now in part 2, let’s see the implementation of slope graphs in Power BI.

—— place video 2 here —–

Now, let’s proceed with the last part and transform the slope graph into small multiples.

—— place video 3 here —–

Before concluding, below is the interactive report from the example of this post:

—— place Power BI report here —–

Take home that combining these two graphic methods produces a high-density visualization that is inevitably comparative. It’s efficient with data-to-ink ratio, space, interpretation, and narrative content for the audience to consume.

Finally, always remember to put numbers in context and always remember to ask: (that metric) compared to what?

Thank you for reading/watching.

 

Book references:

    1. Edward Tufte: Books – The Visual Display of Quantitative Information
    2. Edward Tufte: Books – Envisioning Information
    3. Tufte in Twenty minutes PDF (berkeley.edu)

Blogposts that inspired me: 

    1. Charlie Park – Edward Tufte’s “Slopegraphs”
    2. Charlie Park – A Slopegraph Update
    3. Creating Slopegraphs in Power BI – DataVeld
    4. Power BI Slope Chart: An Overview – Enterprise DNA
    5. Slope Graph with Core Visuals – Explorations in Data Storytelling with Power BI (kerrykolosko.com)
    6. How to make effective slope charts in Power BI — (data-goblins.com)
    7. Kavita Behera’s The Weekly Chart: Slope Graph on LinkedIn (post 1)
    8. Kavita Behera’s The Weekly Chart: Slope Graph – second part on LinkedIn (post 2)
    9. Brian Julius’s response post to Kavita Behera’s Slope graph post on LinkedIn