Choosing the Right Chart: Strategies for Effectively Presenting Data
Presenting Fire Data Effectively Series: Over-formatting
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Fire data isn’t ugly Presenting fire data effectively series Episode: Over-formatting June 2015
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Transcript of Presenting Fire Data Effectively Series: Over-formatting
Fire data isn’t ugly Presenting fire data effectively series Episode: Over-formatting
June 2015
A makeover of fire department data to transform it from unnecessary and confusing to informational.
It’s no secret that a chart can offer quick insight when a table fails.
Microsoft Excel is not just a powerful tool to keep data and spreadsheets. It’s a friend for creating quick charts.
However, just because you can do something to a chart doesn’t mean that you should.
Exhibit: Bar Chart “Formatting free-for-all”
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Say it with me now: Just because you can, doesn’t mean that you should.
The good news is that this chart type is perfectly fine for the data being represented: call volume by hour of day.
Remove to improve A popular mantra in the world of data visualization
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Number of incidents by time 0123456789101112131415161718192021
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Number of incidents by time 0123456789101112131415161718192021
It’s a small thing that your eye barely notices, but avoid using effects like shadow, glow, and soft edges anywhere on a chart. Here, we’ve removed the shadow (right) to give the columns some space to breathe.
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Number of incidents by time 0123456789101112131415161718192021
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We only have one type of information presented here (calls) so the columns really don’t need all the colors.
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Number of incidents by time 0123456789101112131415161718192021
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And since we’re only comparing one type of data, we don’t need the legend at the right. The lesson here is to get rid of ink that doesn’t help.
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Speaking of unnecessary ink, let’s drop the background texture and color. Already, the amount of work for your eyes is reduced and now we can make the chart bigger
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We don’t need the “beveled” effect on the slides. Flattening them out gives our eye a continuous line that doesn’t have to compete with the highlighted top. We’re looking pretty clean at this point but we can keep going.
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The chart title clearly provides what we’re measuring, number of incidents, so we can drop the left legend. Try to avoid bold text (title) as it can get blurry, especially when printed. I moved the title to the left out of personal preference. Western writing starts at the left, a habit for our eyes.
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Our maximum calls in any given hour is 244 but the chart extended to 300. Drop the unnecessary space by changing the y-axis maximum to 250. It’s personal preference but I lighten the major gridlines to a grey, making the columns the stars they are.
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“Truncate” an axis It’s ok to change the maximum but never change the minimum from “0” without doing some extra work.
There are times when you need to emphasize small changes between values. One way to accomplish that is to “truncate” the Y-axis, which changes the minimum value. If you truncate, make two charts: one with the Y-axis at “0” and one with a truncated axis, with a note referencing the full chart.
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Most people won’t notice if you truncated an axis but the ones who do will appreciate both charts. Consider checking out the book How to Lie with Statistics by Darrell Huff for more.
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“Narrow axes can make small and inconsequential changes seem
big, but-symmetrically- zero-axes can make big and real changes
seem small. What matters isn’t some iron rule like ‘Always have a
zero-based axis!’, it’s your prior commitment to being honest with
the data.”
-Kieren Healy
Duke sociology professor
Help your reader Make sure that you have clear labels. Don’t assume your readers will intuitively know what it is they are looking at.
A layman may not realize the hours are in 24-hour clock, starting at midnight. We can add a legend to the bottom, specifically stating the measurement. Working memory generally taps out at 3 items and the legend simply helps that memory keep rolling.
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Number of incidents by time
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Hour of Day, 24-Hour Clock
Number of incidents by time
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Hour of Day, 24-hour clock
Number of incidents by hour of day
We could stop here, but if you have a direct message consider coming out and saying it right in the chart title and adding a bit of emphasis.
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Hour of day, 24-hour clock
Based on our call volume per hour, we might consider moving scheduled shift changes to 6am, rather than 7am. Call volumes begin increasing immediately at 7am. This would allow more time for the current shift to finish duties, rather than being constantly on calls up to shift change.
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Hour of day, 24-hour clock
We can control where a reader’s eyes focus by using color. In this case, change the color to a medium grey and put a pop of color on one column.
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Hour of Day, 24-hour clock
Number of incidents by time
Over-formatting hurts Charts are meant to inform, and they do this quite nicely when they are clean and simple.
Hello! I’m Sara Wood and I love converting fire service members into
NFIRS operatives. I’m currently the State NFIRS program manager for
Kansas and enjoy providing classes and help to bring fire departments
into the era of data driven decisions. If you need help creating a
presentation or analyzing your data, I’d love to hear from you!
