Presenting
Data and Information
given
by Edward Tufte June 19, 2001, Palo Alto, CA
Below
are my notes from this one-day class. Edward Tufte is one of the few very "rich"
presenters I've encountered before -- there's no unnecessary repetition of content or other
filler. I found myself really mentally involved with the class throughout the day. Tufte is a really
gifted teacher/presenter; I left the class full of enthusiasm and excitement for the material he
covered.
Disclaimer:
There's no way that my notes could do justice to this class, and they are done
mainly for my own later reference. But they are provided here as a jumping-off point towards
more specific and useful information. Much of Tufte's material could be described as "common
sense" - - but unfortunately, it's not all that common.
There
are two central issues in the general problem of the display of information:
General
principlesInformation design should always be credited. Not only should the work be
credited to give credit where it is due, but it should be done as documentation and to add to the
credibility of the work; named work implies that someone stands behind it.
"This
is where God wants footnotes."
- Tufte, joking while pointing out that his books feature side- notes, not footnotes that require
one to jump to other parts of pages or (worse) other pages.
Use
direct labeling; legends or keys usually force the reader to learn a system instead of
studying the information they need.
There
are two main ways to escape flatland: you either have to build a model, or you have to
be very very smart. As an example of the very very smart, Tufte used the famous Napoleon's
March chart to go on to illustrate the "5 grand principles of information design":
Good
information design can never salvage poor content. Good content must have these
characteristics:
Additional
principles of information design:
This is where resolution is most limiting; for example, computer monitors cannot
really
show much in the typical "eye span". Information presented on computers is often
"stacked", causing users to ask the frequent question, "Where am I?".
-
Use
small multiples -- the small multiple is a useful way of showing time, by showing
several small images and how they are changing through time, within the eye span. This
convention takes advantage of the investment the user has already made in learning
other designs. Also, by showing a mastery of detail, using small multiples also often
adds credibility. (Galileo was able to put 38 suns within the eyespan to present his
observations).
The
"meta-principle" of information design (or, "how are these principles derived?"):
Good
information design is clear thinking made visible.
(unfortunately,
the converse is also true).
Tufte
mentioned that the next book, to be completed in a couple of years, will probably have a
title something like "Beautiful Evidence".
The
principles of information design tend to correlate with the established principles of
analytical thinking. (see page 53 of "Visual Explanations" for a discussion of these principles).
"Chart
junk" -- unneeded extras to be cute -- often indicates stupidity in the underlying
statistical data.
Important:
Always ask "What is the thinking task that this display is supposed to help with."
Scale:
people can always differentiate between differing angles when they are close to 45
degrees (rather than being very steep or shallow). See p. 25 of Visual Explanations --
sunspot cycles. Determining scale needs to take into account what the thinking task is as well
as the integrity of the data.
"Magic"
is a very interesting information design problem, and it can be useful to think about
since the point behind magic tricks is to hide information -- a systematic corruption of
information design (magic=disinformation). To reveal a magic trick in an information design, five
dimensions must be shown: the usual 3 dimensions of space, time, and what is hidden from the
audience.
It
is the content person's constant responsibility to guard the integrity of the data.
Presenting
financial data
To
be useful, financial data needs to show an assessment of change (this is the thinking question
in this case).
Using
empty vertical space to show a zero point that never occurs does not help, (p. 74,
Visual Display of Quantitative Information). Re-measuring will usually move data closer to
the average ("regression toward the mean) -- more horizontal space can actually show more
useful information in many cases.
The
content should be rich, not the design. -- the variability of data around the
mean/average should typically be the focus of it.
Standardization
of data: any financial data shown over time for over 1-2 years must adjust for
inflation to be accurate. However, seasonal influences can often be appropriately adjusted out.
Do
not trust an information display if there are not notes, references, documentation, sourcing.
The source of the data must be documented for the display to be credible (p. 38, Visual
Display of Quantitative Information).
Bring
in explanation of causality via annotation (p. 56-57, Envisioning Information - using the
idea of gesture/pointing, small but effective).
"Don't
get it original - - get it right."
-- Tufte on copying the techniques of effective displays
Look
for standard kinds of financial data, and do what they do -- these are effective techniques
(for financial data specifically, see the NY Times or Morningstar). Use the conventional great
designs -- the effort into finding out what works has already been made. Learn from it.
"Spark
lines" -- very small displays of a stock's performance over a year -- puts a great deal of
dense information in a very small space. This amount of information is only useful when it is
made visual. It also helps overcome the bias inherent towards "recent" data. (I have an
example of these spark lines to show stock performance on paper that I can show you if
interested. -t)
Web
site or kiosk design
Tufte
commented that every time he hears something like, "We need a metaphor" in relation to
a web design, his heart sinks.
(See Visual
Explanations, p. 146; in general, this is the book that is probably most useful for
web designers)
Metaphors
are usually not effective (eg. trying to replicate the structure or visual design of a
book on a web site). Often most used, and most ineffective, is the metaphor of the binary
structure of computer data itself. (Get halfway, make a choice, get halfway there again, make
another choice -- binary splits)
One
of the biggest problems in web design is that "turf" between the different sub-
divisions of an organization is revealed (and is irrelevant and distracting) to the user.
Tufte
does not believe in deeply hierarchical web displays and believes as much as possible
should be shown immediately -- eg. Excite has an effective display with 162 links, yet does not
appear over-crowded. It is essential to let the user know the scope of the domain of
information right away.
Content
is the only real thing that makes a site unique (and rarely is the content the design).
Content must be delivered to be successful.
Tufte
claimed that one study of web usage indicated that the time of average download exceed
the time of the average visit -- users leave before the entire page is presented. He also claimed
that there was a study showing that, on average, people spend more time waiting for Windows
to load than they do making love. (We did not get a visual display of these statistics. -t)
The
ten most widely hit sites have over 100 links on their opening page.
"Clutter"
is a problem of bad design...you can't show enough information on a computer screen
to have clutter unless it's something you can solve through design. (I would note that this is
assuming the designer is allowed to solve it...advertising and branding can be a form of
clutter that can be difficult to deal with. -t)
One
type of way to evaluate: determine what proportion of the screen is dedicated to "real"
content. If 80% or above, you're probably on the right track.
"If
the design is the first thing visitors notice about a web site, you probably have a problem."
Search
engines
(This
discussion happened while waiting for people to return from break)
The
best meta-search engine will only turn up about 40% of the related material available on
the web. Domain search engines (domain=subject-specific, not domain name) are a better bet
for finding information.
Tufte
used SETI@home as an example of a site that is well- designed from a sociological
perspective as well as for the presentation of technical data.
Recommended
web sites:
Information
displays and decision making
The
annotated medical chart from Visual Explanations, p. 110- 111 was discussed. Tufte
also mentioned the problems of digitizing data and privacy (giving an example that Tonya
Harding was admitted to a Portland hospital, and how records showed hospital employees
were viewing the medical records unnecessarily because of her celebrity status).
Also
discussed here was the very interesting Challenger space shuttle story (Visual
Explanations, p. 38). Essentially, the engineers and rocket manufacturers knew that disaster
was probable and tried to convince NASA to cancel the launch. Tufte approaches it from the
perspective of information design, and shows how much more compelling the data was when
presented a different way.
Demands
to make of a presenter:
-
Show
me causality
- Show me all of your
data (omissions are suspect; Tufte says that if a presenter makes
the claim that "it would be too much to print out", your response should be "that's what
6pt type is for, let's see it."
- Demand the right analysis
(very difficult to do in a group setting). View everything
as selective evidence out of thousands of possibilities. Tufte recommends getting
physically away from the presentation setting to take a break to ask, "What do I really
need to know?". Hard, blunt, direct questions may need to be asked for important
decisions
Principles
for making presentations
Show
up early...you can fix any problems with the presentation setting, and it's also a chance to
meet audience members (they will often leave immediately after).
Never
start the presentation by apologizing.
Early
in the presentation, give an overview of what the problem is, who cares about it, and
what the solution is.
Stumble-bum
technique is very daring, but some have used with success -- eg. high school
math teacher presenting to mathematics professionals, makes intentional mistake during first
proof -- audience follows carefully thru rest of presentation, hoping to catch other mistakes.
See
how long you can go without using first person language.
Particular
- General - Particular (PGP - see Visual Explanations p. 68-71) -- when
explaining an information display, first point out something specific the audience can learn from
it; then give a general overview of what is shown, and follow it with another (different) specific
example.
The
"Law" of presenting -- Always give everyone at least once piece of paper to show
some responsibility for the data (implies that you stand behind it -- they can refer to and ask
about it later). Paper is the highest resolution display device there is. (Tufte describes the
evening news -- 21 minutes that manages to get about halfway thru only the first section of the
New York Times. In 21 minutes, most people can pretty much read thru the entire New York
Times...or 2 USA Todays...or many SF Chronicles...). Also: "A paper record tells your
audience that you are serious, responsible, exact, credible." (quote from his web site).
Ask
what your audience already reads -- what do they already know, what visual displays are
they already familiar with? Use similar materials.
Assume
that the audience is worthy of your respect and that they are intelligent. Don't insult
their intelligence by "dumbing down".
Use
humor to reinforce points -- but it must be very specific, not just a random joke thrown
out. And, of course, avoid offensive humor. "Alienate the audience on the merits of your
content, not by an inappropriate joke." :-)
Don't
use male pronouns exclusively...per the Oxford English Dictionary, plural pronouns are
fine to use and he recommends this.
Affect
is carried by body language -- let people see your honest enthusiasm...don't hide behind
podiums, etc.
Finish
early -- you'll be an instant hit. Tufte said that no one ever left a presentation thinking,
"Gee, I wish he would have gone on for another 20 minutes."
Practice,
rehearse -- this is difficult, requires effort...so what. Use video tape and watch for
distracting gestures and filler talk (uh, uhm)
The
best way to improve the presentation: improve the content
Closing
Animation
presentations were shown:
-
The
"severe storm/severe grid" animation redesign (available on the web here ; another
version here ; and a paper about the process can be found here -- the PDF link at the
top right corner of the page is probably the easiest version to deal with)
- The Viz-O-Matic: The
Dangers of Glitziness and Other Visualization Faux Pas
(hilarious animation, vailable on the web as a Windows Media file here )
- The Music Animation Machine by Stephen Malinowski
Thanks
to Patrick Geille for the updated links to the storm and Viz-O-Matic animations!
Tufte
closed the class with a reading from "Haroun and the Sea of Stories" by Salman Rushdie
(appears on page 120 of Visual Explanations).
1. McKinsey Research
