Dashboard Design Mistake #6: Forcing users to do the math

Klipfolio - dashboard design tip 6

The main raison-d’être of a dashboard is to enable decision-makers to consume information quickly. The design mistakes we’ve discussed in this series all have one thing in common: They all sloooow the user down.

In this final post in the series, we’ll look at a common dashboard design mistake that can drastically increase the amount of time users spend trying to make sense of the information on even a fairly simple dashboard. Let’s call it “forcing the users to do the math.” It is characterized by presenting information in a way that forces users to do calculations themselves to get at what they need.

What if you were a Sales Manager and you were presented with the following chart:

Dashboard Software - Monthly Sales vs. Target Sales

Seems clear enough at first glance, right?

But you would quickly realize that it isn’t easy to get the answers you want the most from this chart:

  • Which months were below target?
  • Which months were above target?
  • And by how much?

You can answer these questions, but you’ll have to compare the distance between the “sales” line and the “sales target” line, month by month, in order to see the overall picture and spot exceptionally good or bad months.

Now as a dashboard designer the question you need to ask yourself when you build dashboards like this is… “Why am I irritating my users off by making them work to get the answers they need”. Instead you should be giving them this:

Dashboard Software - Monthly Sales vs. Target Sales

Much better I’m sure you’ll agree but not quite there. The Sales manager would most likely want to see the actual sales values for each month and the trends. Something like this:

Dashboard Software - Monthly Sales vs. Target Sales

This new chart offers the best of both worlds:

Rapid insights into how sales compared to targets across all months (bars)


Actual sales values and overall trends (line).

Tips for understanding when you are making your users do mental math

How do you know your users are not getting what they want? Watch them as they review the information on their dashboard. These clues are signs your dashboard should be doing more math for your users:

  • They look up at the ceiling in concentration or point at the screen as if to not lose their spot.
  • They constantly look back and forth between two charts. Could you combine the measures in both charts into a calculated value?
  • They scribble numbers on a pad, or use Excel, or a calculator.

Providing a fully usable dashboard requires some thought on the part of the designer. It’s one more reason why it’s crucial to develop a solid understanding of your users’ jobs, concerns, goals, etc.

Become a Dashboard Designing Hero

klipfolio - design hero

If you want to be a dashboard design hero to your users then build the ultimate calculated value: a composite score.

Imagine you are building a sales dashboard that shows a list of customers with metrics like:

  • Days since last purchase
  • Number of purchases in past 12 months
  • Days since last contact

After talking with the sales team, you discover that they frequently use that information to try to identify customers who are at greatest risk of defection to a competitor.

Mentally combining these three numbers to get the overall sense of the likelihood of defection for hundreds of customers requires the sales team to do some pretty nasty mental gymnastics.

Define and calculate a “Defection risk score” that combines all three for them and you’d not only save them time but you’d ensure the math was done right each time.

The math behind composite scores can get a little hairy. But if you’re able to create a calculation that even remotely approximates the mental process that users were going through beforehand, you’ll definitely be a data hero. This resource will help if you want to give it a try https://en.wikiversity.org/wiki/Composite_scores

There’s lots more to learn about dashboard design. But if you’ve been following since the first post in this series, you’ve seen that even a little knowledge goes a long way toward delighting users.

To really go to school on Dashboard design I strongly recommend:

Information Dashboard Design by Stephen Few


Originally published February 1, 2016, updated Apr, 09 2021

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