Graphical Display and
Presentation of Quantitative
Information
13 February 2006
What goes into making a good figure?
Based on the work of Edward R. Tufte, The Visual Display of
Quantitative Information
“At their best, graphics are instruments for reasoning about
quantitative information”
Napoleon’s Russian campaign, shown by C. J. Minard
Graphical Excellence
Basic philosophy:
Assume your audience is intelligent
Developing an excellent graphic takes hard
work
• Most graphs, like many other endeavors follow the
80-20 Rule: You can get it 80% done with 20% of the
effort, but the remaining 20% is hard work, and takes
the remaining 80% of the effort.
Clarify by adding more detail, not less
Plots should be data-rich
Maximize data-ink
Data Density = (no. of entries in data matrix)/(area of graphic)
Data Ink Ratio = (data-ink)/(total ink in the plot)
Use multiples for comparisons
Visual metaphors can be useful
Avoid pie-charts -- they are low in data density and do not order data along
a visual dimension
Trellis diagram
showing barley
production at different
sites for two years
(1931 and 1932)
The data are the yields
for all combinations of
site, variety, and year
Small multiples are
inevitably comparative
Avoid chart junk
Chart elements in close
proximity create a
visual interaction
(1+1=3)
Avoid using moiré
patterns, optical
vibration (e.g. crosshatching)
Where possible, use direct labelling
instead of legends
Use horizontal text
Avoid abbreviations
Present Real Data
Visual metaphors are helpful too
The Lie Factor
"The representation of numbers, as physically measured on the surface of
the graphic itself, should be directly proportional to the quantities
represented."
Plots should be:
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Comparative
Multivariate
High density
Able to reveal interactions, comparisons, etc
And where nearly all of the ink is actual data
ink
Small multiples can be visually effective
/Example of a good poster
http://cires.colorado.edu/~brodzik/2005agu/2005agu_pits.pdf
Ask the right questions
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Does the display tell the truth?
Is the representation accurate?
Are the data documented?
Do the display methods tell the truth?
Are appropriate comparisons, contrasts, and
contexts shown?
Slideware is Evil
“Power corrupts, PowerPoint corrupts
absolutely” (Tufte, 2003)
• Presentations should serve the
audience, not the speaker
• It should supplement the presentation,
not be the presentation
Some tips
• Maintain high data density without
excessive text
• Do not abbreviate statements to the
point that they don’t make sense
• Bullet lists do not explain multidimensional relationships so try to use
graphics
• Do not use the AutoContent Wizard!
If Abe Lincoln had had Power
Point:
http://www.norvig.com/Gettysburg/
Designing Scientific Posters
The poster is a large document, not just decorative
All Stations
List the research
objectives
Figures
are large
and
clearly
labeled
The Methodology
section should be short
but contain sufficient
detail
Use graphics
to show your
Results
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MODIS Albedo
It contains an
Introduction that
motivates the
reader to
continue.
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In Situ Albedo
State your conclusion
and be sure they are tied
to the objectives
References
Acknowledgements
Making your poster
presentation matter
• Make the title both informational and
interesting
• Use color and symmetry to make your
poster beautiful
• Someone should be able to read the
entire poster in less than 10 minutes
• Develop your “elevator speech”
• No text smaller than 24 point
More tips
The printed version may look different
from the computer screen version
• Computer graphics use color additive process
(RGB) whereas printers use a color
subtractive process (CMYK)
• Printers don’t have as many color
combinations as computers
• Avoid using saturated colors
Avoid using low-resolution graphics
Your professional demeanor
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No gum
Avoid annoying mannerisms
Dress appropriately
Show up!
Look at your audience when you are
speaking, thank them, shake hands
• Provide letter-sized color copies
• Bring business cards
• Follow up on requests for information
• http://www.swarthmore.edu/NatSci/cpurrin1/posteradvice.htm