There are many great resources out there for data visualization. Some of my favorite data viz people are Storytelling With Data (b|t), Alberto Cairo (b|t), and Andy Kirk (b|t). I often reference their work when I present on data visualization in the context of the Microsoft Data Platform. Their work has helped me choose the right chart types for my data and format it so it communicates the right message and looks good. But one topic I have noticed that most data visualization experts rarely address is the question I get in almost every presentation I give:
How do I tell a story with data when my data is always changing?
If you are a BI/report developer, you know this challenge well. You may follow all the guidelines: choose a good color palette, make visuals that highlight the important data points, get rid of clutter. But what happens when your data refreshes tomorrow or next month or next year? It’s much easier to make a chart with static data. You can format it so it communicates exactly the right message. But out here in Automated Reporting Land, that is not the end of our duties. We have to make some effort to accommodate future data values. Refreshing data creates issues such as:
- We can’t put a lot of static explanatory text on the page to help our audience understand the trends because the trends will change as the data is refreshed. Example: “Sales are up year over year, and the East region is the top contributor to current quarter profit” is true today, but may not be true next month.
- My chart may look good today, but new values may come in that change the scale and make it difficult to see small numbers compared to a very large number. Example: A bar chart showing inventory levels by product looks reasonable today because all products have a stock level between 1 and 50. But next month, a popular new product comes in, and you have 500 of them, which changes the scale of your bar chart and makes every other product’s inventory super small and not easy to compare.
- I can’t statically highlight outliers because my outliers will change over time. Example: I have a chart that shows manufacturing defects by line, and I want to highlight that the dog treats line has too many defects. I can’t just select that data point on the chart and change the color because next month the dog treats line might be doing fine.
How do we form a message with known metrics and data structure but without specific data values?
When people have asked me about this in the past, I gave an answer similar to the following:
Instead of a message about specific data values, I consider my audience and the metrics they care about and come up with the top 2 or 3 questions they would want to answer from my report. Then I build charts that address those questions and put them in an order that matches the way my intended audience would analyze that information. This might include ordering the visuals appropriately on a summary page as well as creating drillthrough paths to more information based upon items and filters selected to help my user understand the reasons for their current values.
While this isn’t horrible advice, I felt I needed a better answer on this issue. So I sought advice from Andy Kirk, and he responded brilliantly!
To the issue of situations where data is periodically refreshed, I see most encounters (ie. the relationship between reader and content) characterised less by storytelling (the act of the creator) and more by storyforming (the act of the reader).
Andy went on to explain, “What I mean by this is that usually the meaning of the data is unique to each reader and their own knowledge, their own needs, their own decision-contexts. So rather than the creator ‘saying something’ about such frequently changing data in the form of messages or headlines, often it might be more critical to provide visual context in the form of signals (like colours or markers/bandings) that indicate to the reader that what they are looking at is significantly large/small/above average/below average/off-target/on-target/etc. but leave it up to THEM to arrive at their own story.
Then he gave an example: “I find this context a lot working with a football club here in the UK. Their data is changing every 3-7 days as new matches are played. So the notion of a story is absent from the visuals that I’m creating for their players/management/coaches. They know the subject (indeed better than me, it’s their job!), they don’t need me to create any display that ’spells out’ for them the story/meaning, rather they need – like the classic notion of a dashboard – clear signals about what the data shows in the sense of normal/exceptional/improving/worsening.”
Andy also agreed that a key aspect of storyforming is that interactive controls (slicers, filters, cross-filtering capabilities) in your report consumption tools give the reader the means to overcome the visual chaos that different data shapes may cause through natural variation over time.
Less Eye Rolling, More Storyforming
If you are a BI developer and have rolled your eyes or sighed in frustration when someone mentioned storytelling in data visualization, try thinking about it as storyforming. Make sure you have the right characters (categories and metrics) and major plot points (indicators of size, trend, or variance from target). You are still responsible for choosing appropriate chart types and colors to show the trends and comparisons, but don’t be so focused on the exact data points.
Many reporting tools (including Power BI) allow you to perform relative calculations (comparison to a previous period, variance from goal, variance from average) to dynamically create helpful context and identify trends and outliers. In Power BI, there are custom visuals that allow you to add dynamically generated natural language explanations if you feel you need more explanatory text (ex 1, ex 2, ex 3). And Power BI will soon be getting expression-based formatting for title text in visuals, which can also help with providing insights in the midst of changing values.
But mostly, try to design your report so that users can slice and filter to get to what matters to them. Then let your users fill in the details and meaning for themselves.