Visual Impact in Presentations, Part 2: Display Data Effectively
- Nathalie C. Chan King Choy
- Apr 14
- 5 min read
Updated: Apr 26
Part 1 in this blog series talks about prerequisites for assembling any presentation and how to get visual impact when you make slides with just text & no graphics. Today, we continue with Part 2 - data slides.
Regardless of if you get 5 minutes to talk or an hour, your presentations are opportunities to inform, persuade, or inspire action. But when it comes to presenting data, things get tricky. You need to distill a lot of information into something clear and compelling.
I really like how Nancy Duarte boils down what you need to think about into 5 rules for data slides in her book "Slide:ology". [1]
Tell the Truth
Get to the Point
Pick the Right Tool for the Job
Show What’s Important
Keep It Simple
Here’s my take on those rules from research and experience.
1. Tell the Truth
Three reasons to tell an accurate story: it’s ethical, it preserves your credibility, and it demonstrates attention to detail. That means:
Don’t cherry-pick data points.
Don’t truncate axes to exaggerate trends.
Don’t skip intervals to save space.
Don’t put 2 datasets on the same axis if those 2 sets don’t have a relationship.
Check your work, so that you can have confidence in your analysis. Especially when presenting to technical or executive audiences, expect questions - skepticism is natural. Once you lose trust, it takes a lot of work to earn it back.
2. Get to the Point
In her book “Storytelling with Data”, Cole Nussbaumer Knaflic [2] gives a nice analogy with oysters and pearls to show the difference between exploratory and explanatory analysis.
Exploratory analysis is what you do to understand the data. Think of it as opening 100 oysters to find a couple of pearls.
Explanatory analysis is what you present to your audience. You're not showing them all your oysters—you’re just handing them the pearls.
In your presentation, don’t walk through the whole analysis journey. Show the insight that matters, and consider distributing the rest as supplementary material if the curious want to do more review later. At most, if the audience expects it, you might give a very short summary of your methodology.
I like to state the point I’m trying to make either in the title or as call-out, so that the audience can spend less brain cycles processing and more brain cycles listening.
3. Pick the Right Tool for the Job
Just because Excel (or Sheets, or LibreOffice Calc, etc.) lets you make a zillion types of charts, it doesn’t mean they are all a good idea.
Here is a quick guide to help you pick a suitable chart for what you’re trying to convey:
Line Charts: Good for showing trends over time.
Example: For tracking open issues week by week.
Bar Charts: Good for comparing discrete categories.
Example: For showing how many tasks are currently outstanding across different teams or departments.
Tip: Stick with horizontal bars if category names are long.
Stacked Bar Charts: Good for showing how sub-categories contribute to a whole, especially over time.
Example: For showing effort breakdown by task type (e.g., dev, test, bug fix) across sprints
Tip: Use a 100% stacked bar chart if you want to emphasize proportions rather than raw counts.
Scatter Plots: Good for correlation or relationship analysis.
Example: For plotting estimated vs. actual task duration to help identify consistent underestimates.
Pie Charts: Use sparingly! Only good for showing a few large, obvious differences as parts of a whole, because angles are hard to estimate. (A bar chart is usually a better choice)
Example: For showing percent allocation of a fixed project budget across high-level categories—like 60% to development, 30% to QA, 10% to training.
Tip: Start the largest slice at 12 o’clock, and avoid more than 3–4 slices
If you want a more thorough guide on chart types and when to use what, I highly recommend checking out the Graph Selection Matrix in Stephen Few’s book "Show Me the Numbers" [3].
4. Show What’s Important
Just like in Goldilocks and the 3 Bears, we don’t want too much data (overwhelming) or too little data (missing key details). To help you trim down to what’s “just right”, ask yourself: “What does my audience need to know?”
For example, if management wanted to know how a project is going, you wouldn’t display a table of the % complete on all the tasks - that’s too much detail. If it’s a project that was extremely well-defined up front with a fixed scope, you might create a line graph with amount of work remaining over time, also known as a Burn-down Chart, to show how much is left and the pace of completion. What would too little look like? If the scope of the project has been allowed to grow or the team realised mid-execution that some work wasn’t accounted for in the original effort estimate, a Burn-down Chart doesn’t let you see the impact of those changes. That’s why I prefer a Burn-up Chart, which plots total amount of work AND completion over time, so that you can see how the finish line has moved and your progress towards it. If my audience also cares about the breakdown of task statuses in what remains, then I use a stacked bar chart for my Burn-up chart (see the image at the top of this post).
5. Keep It Simple
Our goal is not to make the chart look cool or pretty. Our goal is to make it easy to read and understand. That means:
Carefully consider how you use colour. Highlight what is important and make it stand out with good contrast. Use typical associations (e.g. green is good, red is a problem, grey is less important).
Don’t use 3-D effects, gradients, or shadows because they make it harder to determine the value on the axis.
Steer clear of donut charts (because arcs are harder to estimate than angles) (Rant: Why do Jira dashboard widgets give donuts by default!?!?)
If it’s unruly to show everything in 1 chart, consider breaking down your message into more digestible pieces across multiple charts.
Now go dazzle them with your data slides!
By applying the 5 rules for data slides and focusing on the needs of the audience, you can communicate the key conclusions about a lot of information. Every time you are presenting in a meeting, the audience’s focus is on you, so make the most of it! Even if it’s just a few minutes, you have the opportunity to build understanding, make a point, or drive action.
The next blog post in the series will share some tips for wrangling the tools we use to create effective visual presentations.
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