Thứ Ba, 23 tháng 6, 2009


Graphics and Web Design Based on Edward Tufte's

Graphics and Web Design Based on Edward
Tufte's Principles
This is an outline of Edward Tufte's pioneering work on the use of
graphics to display quantitative information. It mainly consists of
text and ideas taken from his three books on the subject along
with some additional material of my own. This page is in text only
format: in order to understand the concepts you need to read the
books because the concepts cannot really be grasped without the
illustrations, and current video monitor technology is too low in
resolution to do them justice. His work has been described as "a
visual Strunk and White" (here is a German translation of this
Throughout this outline I have included references to the
illustrations in his books that are labeled with the abbreviations
VD-pp, VE-pp, and EI-pp, where "pp" is a page number and:
● VD is "the Visual Display of Quantitative Information"
● VE is "Visual Explanations"
● EI is "Envisioning Information"
1. #Introduction
2. #History of Plots
3. #The Explanatory Power of Graphics
4. #Basic Philosophy of Approach
5. #Graphical Integrity
6. #Data Densities
7. #Data Compression
8. #Multifunctioning Graphical Elements
9. #Maximize data-ink; minimize non-data ink (1 of 13)6/20/2005 3:59:16 PM

Course Topics
Graphics Design
Based on Edward
Tufte's Principles
Setting up your First
Web Page
Acquiring Graphics
From the Web Itself
from Scanners and
Digital Cameras
Graphics File Formats
and Graphic File
Efficient Graphics
Colors, Backgrounds,
Creating and
Modifying Graphics
Using SoftwareHow to Do It
Graphics and Web Design Based on Edward Tufte's Principles

10. #Small Multiples
11. #Chartjunk
12. #Colors
13. #General Philosophy for Increasing Data Comprehension
14. #Techniques for Increasing Data Comprehension
15. #When NOT to Use Graphics
16. #Aesthetics

Tufte's works address the following issues:
● The Problem: The problem is that of presenting large
amounts of information in a way that is compact, accurate,
adequate for the purpose, and easy to understand.
Specifically, to show cause and effect, to insure that the
proper comparisons are made, and to achieve the (valid)
goals that are desired.
● Its Importance: Printed and graphical information is now the
driving force behind all of our lives. It no longer is confined
to specialized workers in selected fields but impacts nearly
all people through the widespread use of computing and
the Internet. Rapid and accurate transfers of information
can be a life and death matter for many people (an example
being the Challenger disaster). The extent to which
symbols and graphics affect our lives can be seen by the
dramatic increase in IQ scores in all cultures which have
acquired information technology: in the United States there
has been an average increase of 3 IQ points per decade
over the last 60 years, for a total of an 18 IQ point increase.
There is no known biological explanation for this increase
and the most likely cause is widespread exposure to text,
symbols, and graphics that accompany modern life. As
mentioned above, this increase has been seen in all
cultures exposed to information technology.
● Its Application: Some of the information relates to the
displays of statistical information, but much applies to any
type of display, even plain text. (2 of 13)6/20/2005 3:59:16 PM

and Web Design Based on Edward Tufte's Principles
● The Solution: To develop a consistent approach to the
display of graphics which enhances its dissemination,
accuracy, and ease of comprehension.
History of Plots
The very first known plot dates back to the 10-th century (VD-28:
first known graph). This was about the same time that Guido of
Arezzo was developing the two-dimensional musical staff notation
very similar to the one we use today. In the 15-th century Nicolas
of Cusa developed graphs of distance versus speed. In the 17th
century Rene Descartes established analytic geometry which was
used only for the display of mathematical functions. But the main
initiator for informative graphics was William Playfair (1759-1823)
who developed the line, bar, and pie charts as we know them
The Explanatory Power of Graphics
The importance and explanatory power of graphics can be seen in
these examples:
● Illustration VD-13/14 shows 4 plots which have a large
number of absolutely identical statistical measures and
properties and yet are very different, as can be immediately
seen from their graphs.
● The Challenger disaster: the data graphs shown to NASA
did not convey the real information which was needed (VE-
47 versus VE-45). If NASA had seen the appropriate, but
very simple, graphics which showed the effects of low
temperature and damage to the solid rocket boosters, the
Challenger would not have been launched that (very cold)
● The Broad Street Pump cholera epidemic in 1854 in (3 of 13)6/20/2005 3:59:16 PM
Graphics and Web Design Based on Edward Tufte's Principles
London, as displayed by John Snow (VE-31: cholera
deaths). This graph showed clusters of cholera deaths
around the site of the pump.
● Illustration VD-166: "communes in France" shows an
extremely dense plot which displays the boundaries of
more than 30,000 communes in France.
Basic Philosophy of Approach
Important rules and themes to use when presenting graphics:
● Assume that the audience is intelligent (a paraphrase from
E.B. White). Even publications, such as NY Times, assume
that people are intelligent enough to read complex prose,
but too stupid to read complex graphics.
● Don't limit people by "dumbing" the data -- allow people to
use their abilities to get the most out of it.
● To clarify -- add detail (don't omit important detail; e.g., serif
fonts are more "detailed" than san serif fonts but are
actually easier to read). And Einstein once said that "an
explanation should be as simple as possible, but no
● Above all else, show the data. Graphics is "intelligence
made visible"
● Data rich plots can show huge amounts of information from
many different perspectives: cause & effect, relationships,
parallels, etc. (VD-31: train schedule, VD-17: Chloroplethic
map, VD-41: Napoleon's campaign, EI-49: space junk)
● Plots need annotation to show data, data limitations,
authentication, and exceptions (VE-32: text of exceptions)
● Don't use graphics to decorate a few numbers
Graphical Integrity (4 of 13)6/20/2005 3:59:16 PM
Graphics and Web Design Based on Edward Tufte's Principles
In addition to "lies, damn lies, and statistics", graphics can also
be used to deceive. For example, deceptive graphics may:
● Compare full time periods with smaller time periods (VD-
60: Nobel prizes, which compares 10 year time periods with
one 5 year period)
● Use a "lie factor" [= (size of graphic)/(size of data)] to
exaggerate differences or similarities
● Use area or volume representations instead of linear scales
to exaggerate differences. See VD-69: "Shrinking family
doctor" as an example of how to confuse people using 1
versus 2- and 3- dimensional size comparisons. Area and
volume representations fool people with the square/cube
law: an increase in linear size leads to a square of the
increase for areas and a cube of the increase for volumes.
● Fail to adjust for population growth or inflation in financial
● Make use of design variation to obscure or exaggerate data
variation (VD-61: exaggeration of OPEC prices)
● Exaggerate the vertical scale
● Show only a part of a cycle so that data from other parts of
the cycle cannot be used for proper comparison
Graphical errors may be more common today than in the past due
to the easy and frequent use of computers. Guidelines to help
insure graphical integrity include the following:
● Avoid chartjunk
● Don't dequantify: provide real data as accurately as is
reasonable. For example, ranking products as better or
worse according to one criteria when several factors are
involved is often not useful unless the magnitudes of the
differences are indicated.
● Don't exaggerate for visual effects, unless it is needed to
convey the information. Sometimes such exaggerations are
essential: for example, it is virtually impossible to show
both the size and the orbits of planets at the right scale on
the same chart. On the other hand, illustration VE-24:
"Exaggerated vertical Venus scale", shows such dramatic
mis-information, that one researcher called for the
formation of "a flat Venus society".
● Avoid dis-information: thick surrounding boxes and
underlined san serif text make reading more difficult (5 of 13)6/20/2005 3:59:16 PM

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