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DATAVISUALSChristopher J. Brown
@bluecology
www.seascapemodels.org/dataviz
Sophisticated dataviz
Source: www.cifar.ca
Mean = 0.5SD = 2.7
Summary statistics
Data: github.com/stephlocke/datasauRus
All these datasets have the same mean, SD and correlation.
Source: sciencebasedmedicine.org
Structure of this talk
1. Tools for dataviz2. Eleven principles for effective dataviz3. Repeat classic dataviz experiment4. Breaking the rules5. R the integrator
R code at www.seascapemodels.org
Tools for constructing dataviz
The ideal dataviz tool
•Sensible and clean defaults• Fast and convenient production of common graphics•Convenient to plot statistical models• Flexible enough to realize our creative thoughts
The ideal dataviz tool?
Photo: Rowan Trebilco
R and the Intergovernmental Panel on Climate Change
Data entry + merging
Maps
Graphs
Word processing
Analysis
Integrating tools
Interactive web content
Data entry
Data mergingMapsGraphsAnalysis
Word processing
+
Integrating tools
R is a flexible tool
• Flexibility is also it’s weakness•Hard to start•So many options to do the same thing•Steep learning curve•Often combine with other tools, e.g. Adobe Illustrator, Libre office (free), Gimp (free)
When should I use ggplot2 or base R?
Simple charts Complex charts
Use base R
Use ggplot2
Eleven principles for effective dataviz
1. Plot your data
2. Clarity not Simplicity
Image: Google Earth
2. Clarity not Simplicity
Figure: Mann et al. Geophys Research Letters
3. Dataviz are models of your interpretation
“Any visualization is a model”
Alberto Cairo 2016
Your own vision is a model
3. Dataviz are models of your interpretation
3. Dataviz are models of your interpretation
3. Dataviz are models of your interpretation
3. Dataviz are models of your interpretation
p < 0.001 for both
4. Visualise your models
4. “Superplots”
5. Length is most accurate for comparisons
Cleveland and McGill Science 1985
Length - aligned
Length
Angles
Area
Hue
Intensity
Accurate
Generic
Length is easier than volume or area
Length is easier than volume
Volumes are hard
Image: KeepCup
Length is better than angles and area
Mariani et al. 2015 Frontiers in E & E
While we’re on the topic of maps…
Brown et al. some time ago
Length is better!
Cawthorn, Baillie and Mariani 2018
6. Scaling matters
Compare these:
Source: viz.wtf
6. Scaling matters
6. Scaling matters
7. Choosing units
Source: vaccinationcouncil.org
Dea
ths pe
r 100
,000
Source: sciencebasedmedicine.org
7. Choosing units
8. Less ink is more: Dataviz from excel 2003
Less ink looks cleaner, less distracting
Minimal ink
-0.5
0.0
0.5
-2 -1 0 1 2x
y
9. Choose colours for more than just their looks
Colour scales
Cinner et al. 2016 Nature
Colour bar makes the yellow (5.8) look specialNot visible to red‐green colour blind
Colour scales
Effective use of colour scales
Colour scales: colorbrewer.org
10. >7 elements is hard to interpret
Source: huffingtonpost.com.au
Source: sciencebasedmedicine.org
11.Good data are easy to visualise
Quiz
To find the quiz use your device to navigate to:
www.seascapemodels.org/dataviz
Breaking the rules
When a pie chart makes sense
Source: choosemyplate.gov
Sophistication helps when: Details matter
Source: Dalin et al. 2017 Nature
Being sophisticated is learning new skills
Source: Dalin et al. 2017 Nature
R the integrator
@bluecology www.seascapemodels.org/dataviz
Total number of people in the shopping centre
Change the world
The “hockey stick”
• Speaks to scientists and public
Vaccinations
Source: The Wall Street Journal
Get inspired
•The Truthful Art by Alberto Cairo•datavizcatalogue.com•Books by Tufte•Twitter: #dataviz•WTF Visualizations: http://viz.wtf, Twitter: @WTFViz•R code on my webpage: www.seascapemodels.org•Take our next R course at UQ (Feb 2019)
Conclusion
•Aim for clarity, not simplicity or sophistication•Experiment to find the best way to view your data•Dataviz are models that aid interpretation•R can help you experiment with different models