Quantitative facts and data can be very powerful for supporting your message, but they may cause confusion if not presented legibly on a slide.
Picturing data is hard
Why does it go wrong so often, when numbers and quantities are displayed visually?
- It is very hard to pick the right numbers to present from a defined set of data, usually drowning us with overload. Which should I show? The absolute values, % of the total, % growth, margin %? Huh?
- There are so many data charts to choose from, pie, column, line chart. Which is the best?
- The standard data templates in PowerPoint, Excel, and Keynote appear cluttered. How do I make data look clean and clear?
One message per chart, especially in data charts
The “so what?” angle to data
Let’s start with the first issue, and get in grips with how to survive in the overflowing data world. My basic training as a consultant at McKinsey taught me a useful concept called the “so what?” of a chart. This pinpoints the essential one fundamental message of a data chart, so all other facts, figures or graphs should serve this purpose alone. In your presentation, clarify this point to yourself, and support this one key concept only, nothing else.
So, before designing your chart, you must pinpoint what it is you want to say. For example, our sales in the US are growing in dollar terms, US sales are becoming increasingly important in our portfolio, growth rates in the US are slowing down, a drop in volume is offset by an increase in prices. While the same data set can answer all of these, and each requires a completely different type of chart for its visualization. Decide on the most important trend that you want to show. Once you have defined it, picking the right data chart type is easy.
Of the many different types of charts available in Excel or PowerPoint, I tend to use only a few. Here is my short list.
- Column chart: good for indicating progression over time, in sales or profits and users visualization.
- Bar chart: used for ranking, the largest players in an industry or the lowest cost producer. Make sure you sort your bars in ascending or descending order, to add an additional visual clue about the relative position of a number in a series.
- Stacked column chart: good for depicting market shares, or components of a whole. I like these better than pie charts.
- Line chart: used for displaying a trend made up of many data points, for example, world population since 1850, and for visualizing multiple trends together on one chart. Make the line of such charts really thin, to let it stand out on the screen.
3D charts are harder to read than 2D ones
Manual design in 2D
The standard data chart templates in PowerPoint and Keynote are ugly and cluttered. Here are some fixes you can do to make them look cleaner.
- Remove tick marks and grid lines and make the axes thicker.
- Remove the automatically generated legends, and make your own instead. Use larger boxes better positioned on the slide as an entirety.
- Remove and create your own slide titles, positioning them manually on your slide so they line up with all other elements on it.
- Set spacing between two columns or bars to 50%.
Keynote and PowerPoint offer a wide range of 3D data chart templates. However, 2D designs look much better, and are also easier to read, with bars lining up better neatly next to each other neatly.
Newspapers such as The Economist or the New York Times often use data charts that have a simple, clean style. Try to replicate this in your own presentation.
Data charts in Excel, used for analyzing, slicing, and dicing data, can (and should) be generated automatically. If you are not 100% sure what the key trends are, and you need to quickly draw and change data charts, automated charts are great time savers. Once you are ready to design the presentation, you’d have hopefully passed this stage. To present your conclusions, spare the audience the effort of going through the data analysis process. You’ve done the hard work and can feed them the answer directly. To do this well, you must carefully design data charts manually, answering to your “so what?” definition. A quick cut and paste from Excel will not do your presentation justice.
Round up numbers to make them clearer and appear more credible. $52.3M is easily grasped in comparison with the full $52,345,548 number. This also makes the presentation look solid. While it’s important your Excel model calculates everything with full precision, only to hand you complete, long numbers, your audience probably won’t buy into your exact prediction of year 5 sales yielding $52,345,548, precisely. So, save everyone the trouble and round up your numbers.
You can take this to another extreme, by applying ranges using only the mean number, for example, 7 for a 5-10 range. This could work, for one single data point, but once additional variables are involved, you’ll need to include them in your calculations too, making everything very confusing. Instead, offer a big caveat upfront, and continue to work with your point estimates throughout the presentation.
Charts are only the beginning
Even the most minimalist data charts can be hard to grasp by audiences. To simplify things, add text boxes, arrows, lines, circles, and apply all the drawing tools available to accentuate your point. A big arrow across columns can readily indicate growth, a circle around the turnaround in gross margin will emphasize it, etc.
It’s not a chart you’re designing, but the slide as a whole. Where more than one graph appears on a page, align and distribute them properly, with all the horizontal axes lining up. Draw a temporary line across them to double-check, and make all the charts roughly the same height. Take notice of titles and other objects’ positioning and alignment on the slide.
Yes, it is wrong to lie with statistics. I refrain from breaking axes or using other tricks to stage a modest growth as a huge jump in sales. On the other hand, poor design can damage your case. For example, if you only have two years of sales data to show in a column chart, stretching it across a 16:9 screen will flatten sales trends. Instead, shrink the chart until it fits well right in the center of the screen.
Putting things in perspective
Sometimes numbers are so small, or so big, that audiences are virtually unable to grasp them. A slide stating the world’s population of 7 billion is meaningless to people. You need to conjure up a quantitative metaphor that tangibly compares your values. For example, liken the emptiness in an atom to the space around a strawberry located in the middle of a football field, its electrons flying round on the podium seats. If you add such a metaphor in text, or, better yet, accompany your slide with a picture of an empty stadium and a tiny red dot in the middle, the information is sure to resonate well with your viewers.
Not all data charts have to be simple, containing only several figures. To convey a message that numerous instances exist for something, you can show a world map covered with dots.
The message of a chart must always be easy to grasp, but may require complex charts that weigh it down. Instead, consider using props, such as real live pictures. Where possible, bring the real thing in and demonstrate it on stage with you. In a presentation I recently attended, a picture was shown with several empty bottles of soft drink above a bag with the corresponding amount of sugar they contain. It served as a very convincing data visualization prop.
Every analysis is always accompanied with extra information, unit measurements, footnotes, data sources. Ultimately, all this information should fit on the slide, somewhere. This is especially true where you’ll want to reproduce analysis of an older deck version, or drill-down into its substance. Keep in mind that this information serves best as secondary input. You do not want to overdose your audience with too much clutter as they first see the chart. Place such data in small font or soft colors, to hint they are less pertinent to the chart, and are optional for reading. You’ll find most of your audience will skip them.
Sometimes, a simple data table is best
Sometimes, you do not need a data chart at all, and a handsome table containing rounded numbers might just be the right option with which to visualize your data. This works great for detailed financial statements, or in situations where a chart contains numbers with completely different orders of magnitude.
Here are some quick improvements you can make to any table (Image 6.2):
- Space out rows and columns, the more they are the same size, the calmer the look.
- Round up numbers to a reasonable precision level, and use a comma to separate numerals.
- Right-align numbers, and make sure they are aligned on the decimal point.
- Right-align the first column with its descriptive text, so that it’s as close as possible to the first column with numbers.
- Use highly muted backgrounds. I usually pick the lightest shade of grey, and color the cell borders white.
- If necessary, reduce font size. Very big fonts with unnatural line breaks do not look good in a table.
- Enter data manually. Meticulously typing in every number is often the only way to give your table the look you want. Invest the time and do this. It’ll prove well spent.
As you work on visualizing data, remember that people get used to interpreting info in a specific way. Think twice before you dramatically reinvent methods for visualized numbers in your presentation. A company’s Board of Directors, for example, has become accustomed to seeing quarterly results from dozens of previous quarterly presentation. These have trained the Board Members to think about data in a certain way, which is hard to change.
Some presentations leave you with no other option but using a dense data table. For example, quarterly results presentations require the accounting data to be presented without rounding off errors. In such cases, add the table of raw data to the deck, but use a selective data chart to highlight apparent trends.
Where is the meat?
It is tempting to cut the amount of data in your presentation and simplify your story, but an important distinction between evidence and detail must be maintained. While detail can be cut, crucial evidence must remain intact. Go ahead and replace a slide that ranks market shares with the single textual sentence “We are the largest in our industry.” Yet, presenting the actual data, or naming your (much smaller) competitors, can prove much more powerful. This is especially helpful to people that hear your story for the first time.
I often find data I present does not reflect what’s really going on. You may need to go back to your analytical drawing board, recut numbers, and bring trends to life in your presentation.
A favorite analysis presentation tool I learned back at McKinsey is the Waterfall chart, also called the Source of Change chart. This is a stacked column chart in disguise, explaining how values are bridged (for example, this and last year’s profit) using a number of drivers that follow the same or opposite direction.
The most difficult aspect of the waterfall analysis, is calculating the actual numbers. Once you have figured those out, it is relatively easy to place them in PowerPoint.
Data charts should be helpful
Data visualization can sometimes be taken too far. Today, the infographic is a very popular way to visualize data. These are cool, cute, and nice, but a closer look shows they often fail in helping you better understand data. Graphic design is used for cosmetic purposes only. Simple visualizations of one single trend prove to be the clearest.
Quick sum up
Data charts should have one “so what”, and focus the entire chart on that message. Resist the temptation to cut and paste from your spreadsheet, but rather design the chart from scratch, manually if you have to.