episode: pie is rarely a good idea
TRANSCRIPT
Fire data isn’t ugly Presenting fire data effectively series Episode: pie is rarely a good idea
July 2015
A makeover of fire department data to transform it from unclear and underperforming to powerfully informative.
Microsoft Excel is not just a powerful tool to keep data and spreadsheets. It’s a friend for creating quick charts.
However, you are responsible for choosing the right chart type. Choosing the wrong chart can kill your data.
Exhibit: pie chart There are better choices
Other, 9%
Abdominal Pain, 10%
Cardiac, 15%
General Weakness, 17%
Respiratory, 20%
Neurological, 21%
Initial Patient Complaint
Biology is against pie The human eye perceives height and length easily, not angles of areas in a circle
Pie charts are great when emphasizing parts of a whole but stick with a max of 3 categories. A high number, a small number, or an even distribution can be presented fairly well with a pie chart. Even better if you add a callout stating what the reader should take away from the chart!
88% of our FD members are male
12% of our FD members are female
Our membership consists of almost an equal amount of males and females.
Better chart type Bar charts and column charts are perfect when comparing categories
For this data we’re really just interested in the prevalence of each complaint. Both charts quickly convey some sort of answers.
Note: I’ve left both charts at default view. We’ll clean them up in a minute.
0%5%
10%15%20%25%
Initial Patient Complaint
0% 10% 20% 30%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
When working with charts that have long labels, the column chart falls flat. It forces the axis labels into some funky angles or even worse, fully vertical. This is not nice to your readers.
0%5%
10%15%20%25%
Trau
ma
Oth
er
Abdo
min
al P
ain
Card
iac
Gen
eral
…
Resp
irato
ry
Neu
rolo
gica
l
Initial Patient Complaint
0%5%
10%15%20%25%
Initial Patient Complaint
Instead, try on a bar chart. This type of chart can handle the long bar labels. Bonus: your reader doesn’t have to hurt their neck! Now let’s work on improving the default chart.
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Start by removing the default bolding on the title. Bold text is difficult to read and does not look good when printed. The letters bleed together.
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
My preference is to shift the axis labels to the top for column charts. It’s easier to read top to bottom. I slightly darkened the bars to a more saturated blue. It’s a small thing you barely notice but would print better.
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint 0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Lighten the gridlines and remove the black outline. This brings the bars front and center, the stars they should be! Your eyes have guidance without being overwhelmed.
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint 0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Thicken the bars to add weight. White space is nice but too much disconnects the categories you are presenting here.
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint 0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Add labels to the inside of the bars. This part is tricky. I added data labels but formatted them to appear “Inside end” under Label Position. You can do this by right clicking any label and choosing Format Data Labels.
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Black labels are not a good choice here. Instead, a nice contrast is created by switching the labels to white. I use the size of the labels to determine if the bars are too thick or too thin. Adjust so the text fits nicely.
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Labeling the inside of the bars allows our eyes to easily find the end of each bar without cluttering the white space around them.
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
It takes the right chart to show off your data. The most beautiful chart won’t help you if it doesn’t meet the needs of the data being presented.
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
Initial Patient Complaint
Other, 9%
Abdominal Pain, 10%
Cardiac, 15%
General Weakness,
17%
Respiratory, 20%
Neurological, 21%
Initial Patient Complaint
If you have something specific to say, format the chart to emphasize your conclusions from the data. A little color and a more detailed title are all you need.
8%
9%
10%
15%
17%
20%
21%
0% 5% 10% 15% 20% 25%
Trauma
Other
Abdominal Pain
Cardiac
General Weakness
Respiratory
Neurological
We need to add training for neurological complaints to the calendar, as we have mostly focused training on trauma and cardiac incidents.
Avoid indigestion Dress your data for presentation, not dinner.
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!