Line charts are just about the most difficult chart to format for clarity. It doesn't take too many lines before the whole thing looks like a pile of undercooked spaghetti.

1. Fire data isn’t ugly
Presenting fire data effectively series
Episode: When lines cross
July 2015

2. A makeover of fire department
data to transform it from
unclear and underperforming
to powerfully informative.

3. This redo is going to be a bit different. Here we’re going to
use some real data from the Kansas Fire Incident
Reporting System on school fires during the school year.
First, let’s create a line chart using all the defaults in
Microsoft Excel. Line charts are a bit big so we’ll be
working with one chart, instead of the usual side-by-side.

4. Exhibit: line chart
Default Spaghetti al dente

5. 0
10
20
30
40
50
60
70
80
90
Fires at schools during the school year
2010
2011
2012
2013
2014

6. 0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
Line charts visualize continuous information. There is no
halfway point between “Vehicle fires” and “Yearly Total”
yet this is how Excel might default your chart.
Instead, make sure that time is on the x-axis by using the
Switch Row/Column option.

7. Line charts
Time series data is suited perfectly
to a line chart since it’s
continuous data. Few other data
series fit well on line charts.

8. We can label the chart better using a formatting option
for the Labels. Did you know that Excel can list the Value,
Series Name, and/or Category Name? Just right click the
labels and choose Format Data Labels.

9. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Directly labeling the lines takes away the need to look at
a line, look for the color, and then assign a name from the
legend.
Working memory can only keep about 3 items going at
once.

10. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
You’ll notice I also changed the colors of the labels to
match the lines themselves. This helps your eye out even
more.
We’ll come back to color here in a bit.

11. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Lighten the gridlines to help the lines move forward. This
ultra-light grey might not print well so check it with a test
run. Drop the bolding on the title, too.
I’ve shifted the title to the left, where our eyes naturally
look for the beginning of text.

12. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Think about what you are trying to say with the chart. If
you are trying to emphasize the fires inside schools, then
you can push the emphasis right there.
Once you know the point you’re trying to illustrate, a bit
of color does all the work for you.

13. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
You can even slightly increase and decrease the line
weight of each category. Don’t go overboard with this
though.
Here, the line for Building/Inside Fires is just a tad thicker
than the rest.

14. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Worried about printing in black and white?
Even without color, your line chart still passes all the
information on, between direct labeling and shades of
grey.

15. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
If you ask your data the right questions you can get the
right chart. If you’re interested in each year compared to
the others this chart is perfect.
Let’s ask our data another question. Are there more or
fewer fires today than 5 years ago?

16. Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
If we only need to compare two years, we’re not
interested in the rise and fall between each year.
Actually, the other years get in the way. Can you tell with
this view if fires are up or down?

17. Slope Graphs
Check out this chart type!

18. Building/Inside Fires
Outside
Trash/Dumpster Fires
Vegetation Fires
Vehicle Fires
Yearly Total
0
10
20
30
40
50
60
70
80
2010 2014
Fires in schools during the school year

19. Building/Inside Fires, 22
31
Outside Trash/Dumpster Fires, 19
15
Vegetation Fires, 8
10
Vehicle Fires, 6 5
Yearly Total, 68
72
2010 2014
Fires in schools during the school year
Slope graphs are just two data points: the start date and
the end date. You can quickly see what’s up and what’s
down.
You can even emphasize increasing/decreasing fires
using color: red for up, blue for down.

20. Building/Inside Fires, 22
31
Outside Trash/Dumpster Fires, 19
15
Vegetation Fires, 8
10
Vehicle Fires, 6 5
Yearly Total, 68
72
2010 2014
Fires in schools during the school year
Be careful in sizing your chart. Slope graphs are usually
tall and narrow, but if you make your chart longer the
increases and decreases will appear smaller. If you make
your chart taller and squish it any changes will show off
dramatically.
Building/Inside Fires, 22
31
Outside Trash/Dumpster Fires, 19
15
Vegetation Fires, 8
10
Vehicle Fires, 6 5
Yearly Total, 68
72
2010 2014
Fires in schools during the school year

21. 0
20
40
60
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Building/Inside Fire
Outside
Trash/Dumpster
Vegetation Fires
Vehicle Fires
Building/Inside Fire
Outside Trash/Dumpster
Vegetation Fires
Vehicle Fires
Yearly total
0
10
20
30
40
50
60
70
80
2010 2011 2012 2013 2014
Fires at schools during the school year
Default
After

22. Lines and Slope Graphs
Don’t be afraid of line charts.
Just clean them up a bit and they
can be quite presentable.

23. Hello! I’m Sara Wood and I love converting fire service members into
NFIRS operatives. I’m the State NFIRS program manager for Kansas and
enjoy providing classes to help 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!