The Power of Big Aggregate Numbers

Big A** Numbers. If you’ve ever created or used an interactive data dashboard, you’ve probably seen a “Big A** Number.” It sits there, right at the top of the page, telling you exactly what you should know.

In the data visualization community, Big A** Numbers—also called “Big Aggregate Numbers” or “Big Actionable Numbers” or simply “BANs”—can help users quickly understand the main takeaway of the data. But BANs don’t have to be limited to dashboards. Whether it’s tweets or presentation slides or reports, BANs carry a lot of power and present great opportunities for data visualization creators to convey their message and insights.

Different Use Cases of BANs

• Dashboards. Maybe the most common way people use and think about BANs are in interactive dashboards. Steve Wexler has written about BANs extensively on his blog, Data Revelations, summarizing their utility in a 2017 post: “BANs can do a lot to help people understand key components of your dashboard: they can be conversation starters (and finishers), provide context to adjacent charts, and serve as a universal color legend.”

• Static (PDF) Reports. In many research reports, researchers and analysts often include a graph or chart because, well, most reports just have them. Some also probably want to avoid what my Columbia University Press editor calls the “wall of words”—the overwhelming page after page of text with no break. But in these instances, you don’t always need to show all of the data. Sometimes a BAN is sufficient. Adding a BAN to the sidebar of a report—which can be as simple as a shaded text box in a Word doc or Google Sheet—can help readers navigate the report, identify the important findings, and encourage them to explore the report in more detail.

• Slides. As I wrote in my book, Better Presentations, a presentation is a fundamentally different form of communication than a written report. In a presentation, you don’t need all of the specific details from the analysis. Here again, a single, large number on a slide—try bumping that font size up to 80, 90, 200—will help bring the most important takeaway forward to your audience. 

Advantages of Using BANs

In any of these use cases, there are four primary advantages of using BANs:

1. Simplicity and clarity. By condensing vast amounts of information into a large, single number, BANs provide a clear and concise representation of the overall picture. This simplification allows readers to grasp complex information quickly.
2. Comparisons and benchmarks. BANs facilitate easy comparisons and benchmarks across different categories or time periods. By visualizing aggregate numbers, users can more easily assess performance, identify outliers, and measure progress.
3. Trend identification. BANs can reveal trends and patterns that may not be immediately apparent in raw data. In dashboards, BANs are often combined with small charts—say, showing the final value next to a line chart—to help users identify patterns and trends over time.
4. Decision support. With BANs, decisionmakers and stakeholders can assess the potential effects of various courses of action. Especially with real-time or near-real-time data, these aggregate numbers can offer a holistic view, allowing stakeholders to gauge the potential consequences of their decisions.

Best Practices for Using BANS

Others have written about best practices around using BANs, which I’ve tried to distill into a list of five here:

1. Define clear objectives. What is the purpose of the BAN in your data visualization? You can only answer that question if you’ve identified the needs of your users. Some of your users will want to dive into the details of the data, moving beyond summary statistical measures like means, variances, and correlations. Others will want the top-line or headline number that can help them get the main takeaways from the data.  
2. Choose the right metrics. BANs are distinct from graphs, charts, and diagrams because they show only a single, aggregate number rather than enabling users to compare different values. When selecting a number to present as a BAN, consider whether it is relevant, meaningful, and aligned with the objectives of the product. When using summary numbers like BANs, it is important to give careful consideration to avoid presenting misleading or biased interpretations of the data.
3. Prompt drill-down analysis. Having said that, while BANs offer a high-level perspective, they also allow users to drill down further into the data. With interactive dashboards, BANs demonstrate the kind of information users can find by clicking through the data, and in other cases, like static reports, BANs can highlight key numbers to encourage readers to explore the text and other graphs and tables in more detail.

There are plenty of ways to create and style your BANs—just walk through a mall or scroll through Pinterest and you’ll find plenty of styles and design. I particularly like this post from Kevin Flerlage, who shows 22 different BAN designs in Tableau and, in this accompanying video, how to make them. Kelly Gupton has a nice post on making BANs more accessible (again in Tableau).

Ultimately, BANs play a pivotal role in data visualization and can provide concise and informative representations of complex datasets. Their ability to simplify information, identify trends, highlight particular numbers, and support decision-making makes them a powerful tool. By following the best practices listed above, you can help your audience best leverage the insights from your data and analysis to make informed decisions.

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