**Edward Tufte Lecture at NASA Headquarters**

**June 2, 2004**

*(Notes captured by David Herring)*

**Opening Remarks**

Tufte began by showing an actual, original printing of *The Starry
Messenger* by Galileo. Galileo began the book with a discussion of the
optics of the new 20x telescope he designed, a vast improvement over the
4x standard telescope of his day. Galileo used high-resolution printing
with images printed from high quality engravings. He showed the first
images of craters on the moon. Galileo then turned his telescope skyward
and observed an infinity of stars. He differentiated from "fixed" stars,
and drew them across the page, symbolizing the infinity, and breaking
conventional layout rules of margin and page space. Tufte's point in
using Galileo's book is that *theories are decided not by philosophers,
but by looking at evidence.* Tufte called this a watershed in human
thinking--- things are decided by how well they fit observed, empirical
evidence. Theories are tested by evidence.

The next night Galileo observed other stars, and night after night he
looked again and again and he sees they change their arrangement
relative to Jupiter. He realizes their appearance and disappearance
means they are satellites of Jupiter in orbit around that planet. Tufte
called attention to the fact that the visuals Galileo drew to illustrate
Jupiter and its satellites are embedded in with the text. They are
presented as evidence within the context of his narrative. Part of
Galileo's point is to tell his story and, more importantly, to present
overwhelming evidence from many many nights of observation. The reader
has to read the story and then decide, "Can I believe him?" From the
reader's perspective, absorbing the information and assessing the
credibility of the report go hand in hand. So as an author, you gain
credibility by demonstrating a mastery of detail.

Tufte said there are two deep, profound, essential details in presenting
information: (1) Communicating a multivariate problem requires
expressions of multiple dimensions. They have to be reasoned and
communicated in 2-D flat lands of paper and computer screens.
Consequently, there have been enormous efforts to express more than 2-D
data on 2-D surfaces. "Escaping this flatland," Tufte said, "is the
essential task of envisioning information, for all the interesting
worlds (physical, biological, imaginary, human) that we seek to
understand are inevitably and happily multivariate in nature."

\(2\) information resolution. There have been vast improvements in the
information we know and can communicate in bits per unit area and per
unit time. We can think of science as improvements in resolution. In
Galileo's time, could resolve at 10^-3^. Today we have had about 45 or
46 orders of magnitude improvement in resolution since Galileo---about
10 million to 100 million times per century. Information resolution,
Tufte says, is a very deep and important concept.

**The Six Grand Principles of Design**

Tufte showed an actual, original print of Euclid's *The Elements of
Geometry*. He noted the title page where credits were given. His point
was that agencies don't do things, data don't do things, *people* do
things. Giving proper credit is a sign of responsibility and shows
ownership. Thoughtful design can eliminate unnecessary legends and
codes, and enhances content-reasoning time and design-figuring-out time.
Strive to *maximize* design, and *minimize* content figuration.

Tufte showed Euclid's book literally had 3-D pop-ups that could be
folded to illustrate geometric shapes, like pyramids and other shapes.
This was done at great expense by the printer to communicate important
geometrical concepts.

• First grand principle of design: **[Show comparisons.]{.underline}**

• Second grand principle of design: **[Show causality.]{.underline}**

Tufte gave everyone a copy of the Map of Napoleon's March during the War
of 1812, designed by Charles Joseph Minard in 1861. The map is a
statistical graphic of the ugly loss of life during Napoleon's attempt
to conquer Russia. Tufte called attention to the fact that the map
adheres to both the first two grand principles of design. (See
http://www.edwardtufte.com/tufte/posters).

• Third grand principle of design: **[Show more than 1 or 2
variables.]{.underline}** Serious problems are multivariate problems, so
show multivariate evidence.

Minard's map shows six variables with real clarity. And it also
exemplifies grand principle of design #4...

• Fourth grand principle of design: **[Integrate word knowledge and
image.]{.underline}** On the map there is a paragraph of words, and
there are annotations all over the map to help interpretation.

• Fifth grand principle of design: **[Document everything and tell
people about it.]{.underline}** Documentation is a fundamental quality
control mechanism and determines credibility. Say where the material
came from and document it. (It is okay to use small typeface for this.)

The map says who collected the data, and details the three different
measurement procedures, and scales of data. Tufte strongly advocates
adhering to all these principles in all our image and graphics designs.
Put a ruler on the picture or do something to put it on the universal
grid. This should be embedded within the image or material. Every image
should be accompanied by some sort of mapping. Tufte said you're not
doing science and not presenting evidence unless you put it on the
universal grid.

• Sixth grand principle of design: **[Presentation stands or falls on
the quality, integrity, and relevance of the content.]{.underline}**
Everything else you do in communications is subsequent to this
principle. Good design cannot salvage failed content. Science is a
content-driven enterprise. Minard's map was an anti-war poster. Minard
hated war. The map poignantly illustrates the "ugliness" of the
Napoleon's march. All the great analytical designs have generally come
from people like Galileo or Minard, who are possessed by their content
and want to share it with the world and tell people what they have found
out.

Tufte noted that the word "Napoleon" does not appear anywhere on
Minard's map. Minard's point is not the surviving celebrity Napoleon,
but rather the enormous loss of life that happened to the troops. So
*sometimes the absence of information also speaks loudly.*

Read Chapter 1 of Tufte's *Envisioning Information*. Galileo was
wide-eyed, undiplomatic, and sardonic in his approach and in his tone,
not unlike physicist Richard Feynman. Both were vivid characters. See
pages 120-121, regarding the rings of Saturn. Tufte again called
attention to Galileo's drawings of Saturn embedded in with his
text---meaning that thinking, reasoning, and evidence are presented as
one, as they should be.

**One Damn Thing After Another**

Galileo has many sequential pages of drawings of the sun and sunspots.
Tufte showed page after page of the drawing in the book and quipped,
"It's like one damn thing after another." The drawings are
high-resolution but their "relentless sequentiality" becomes
overwhelming. This is part of Galileo's strategy---to overwhelm the
reader with the evidence of his high-resolution images.

Humans routinely process 150 MB of information at a glance. Most humans
see in 20-bit color with incredible depth of field. Tufte observed that
it is no wonder the most common user interface question asked by users
when navigating the computer screen is: "Where am I?" The computer
screen lacks the level of resolution that the human eye is accustomed to
seeing.

• Seventh Grand Design Principle: **[Show your information at once,
adjacent in space, rather than stacked in time.]{.underline}** This is a
problem with PowerPoint presentations---they are typically just one damn
thing after another, relentless in their sequentiality. PowerPoint
forces the presenter to stack information in time because the resolution
is so low.

If you're designing a monitoring or assessment system, Tufte said, don't
start with technology at the back but begin with what the user will see.
I want the highest resolution possible monitor that the user will see
and then ask the technology to accommodate it. Typically, this is done
backward -- we start with a solution first and then search for a user.
Unfortunately, software development is driven by two main forces:
marketers and programmers. Rather, Tufte says, we should *start with the
interface* and start at as high a resolution as possible and let that
drive the process.

**Mastery of Detail**

Tufte showed Galileo's sunspot drawings rapidly in sequence to
demonstrate their propagation across the face of the sun as well as
their changes in shape over time. He said, *The way you gain credibility
with your audience is your demonstrated mastery of detail.* Show that
you understand what is going on because you spent a lot of time with
your subject or your audience. *The single biggest threat to learning
the truth is evidence selection.* Human beings select evidence and so in
science we ask that everything be independently replicated. Therefore,
you should demonstrate to your audience that you haven't "cherry-picked"
your evidence to support your point. You can deflect such suspicions of
cherry-picking by using "small multiples" of evidence---some repetition
of data or observations that reinforce earlier data or observations.

**External Forcings in Communications**

Tufte highlighted Galileo's statement in his book that the Earth moves.
This statement was challenged by the church and Galileo was instructed
not to teach that the Earth moves. What had the church to do with this?
We decide theories by looking at the supporting evidence.

**Images and Quantities**

On page 24 of his book *Visual Explanations* Tufte shows a NASA data
visualization of a mountain on Venus (produced using radar data from the
Magellan space probe) in which the topography was exaggerated 22.5
times. When doing things like exaggerating the topography of 3-D
terrain, *you have to tell people.* You cannot imply the exaggeration
represents the truth. You must tell the viewer *on the image* that it
has been exaggerated for enhancement of interpretation in 2-D space. If
NASA doesn't get it right on the label, then those downstream
communicators, teachers, book publishers, etc., will not fix it and
misinterpretation gets perpetuated.

There are no mountains on Venus with greater than a 3-degree slope. So
what is happening in the exaggerated image is a "marketing impulse"
which suggests that 3-degree mountain slopes are boring. There's the
sense we need to jazz things up, hype them, or market them. But Tufte
disagrees. On the contrary, he says, we don't need to hype the science,
nor should we. Doing so damages scientific integrity. Marketing should
leave science & technology alone. "Have faith in it," says Tufte, "NASA
has wonderful material. Let it stand on its own."

**Visual and Statistical Thinking**

Tufte called attention to the graphs of annual sunspot counts, on page
25 of his book *Visual Explanations,* and said, "Get the data action
around 45 degrees." This was in reference to the aspect ratio of the
graphs. Meaning, the data can be exaggerated so as to actually *cloud*
interpretation. The top graph shows very sharp peaks and valleys, but
clouds the point of the gentle downslope on the backs of the peaks. So a
good rule of thumb is to set the aspect ratio of graphs such that the
action shown in the graphs is at about a 45-degree angle.

The map on page 30 in *Visual Explanations* shows a map of London with
the locations of water pumps and nearby houses where cholera outbreaks
were observed. By thinking clearly and showing causally what happened,
John Snow made a persuasive case that changed policy. The bad water pump
was shut down and the cholera epidemic promptly dissipated. Moreover,
this was the last such cholera epidemic in London.

**Effective Communication is Not Magic**

In magic, a good magician never tells people what he's about to do
because people will then seek to figure out the illusion and how it
works. Magic is an exercise in misdirection and obscuring the truth.
Conversely, in communications, do the opposite. *Always* tell the
reader/viewer what you're about to do. This will help people evaluate
your talk and the evidence you present.

**The Smallest Effective Difference**

Make all visual distinctions as subtle as possible, but still clear and
effective. (See pages 73-74 in *Visual Explanations*). Notice how the
lines annotating the parts of the human ear distract from the main
point---the drawing of the ear. Then notice an alternative approach on
the following page in which Tufte remade the drawing with annotations
that don't distract. The latter drawing conveys more information, more
effectively. His point: *Minimal but clear distinctions reduce the
clutter of visual noise in image interpretation.*

Note the color scales used (on page 76 of *Visual Explanations*) in the
cartographic maps produced showing land elevation and ocean bathymetry.
Note how color as a metaphor for the information represented lends
itself to easier interpretation, and allows for a whole other axis of
info to be inserted---the ships' tracks where the measures where
actually made. In contrast, note the rainbow palette used on page 77 to
convey the same information. The latter image is noisy and much harder
to process.

**Clarity versus Detail**

There is no relationship at all between amount of detail and difficulty
of reading. The stronger, more radical position is to *clarify* and then
*add detail*. The way you reduce clutter is to clarify the design and
then add information. There is a common misconception that detail
detracts from readability, but the opposite is true. More details
written clearly and concisely enhance the reading experience and convey
more information.

**New Ways to Show Data**

The most common situation in scientific communications is to have a noun
followed by a number, such as "glucose 128." (Tufte referenced his
article entitled "Sparklines, Intense, Simple, Word-sized Graphics.")
Emphasis is on the term *word-sized*; i.e., simple and intense graphics
that are literally about the same size of words, like this:
![](media/image1.png){width="0.9583333333333334in"
height="0.19444444444444445in"} glucose 128

Tufte's point is that authors can show trend data using such
"sparklines" embedded within their text, the same way Galileo embedded
little drawings within his text. Effectively used, such graphs are about
the size of a word, but convey far more information. In this case,
several axes of information are conveyed at a glance, including the
range of glucose measurements that are considered normal (gray bar); the
trend of the measurements over time ending with the most recent
measurement (red dot) which corresponds with the number "128"---the
measurement's value; and all other values along the sparkline can then
be qualitatively assessed relative to the normal range and the most
recent measure.

About 5% of all data graphics appearing in *Science* and *Nature* are
sparkline-like graphics, Tufte said. They have 300-to-1 aspect ratios
because they have a lot of data. The problem with sparklines is they are
de-quantified. As readers, we will have to face that fact, while
"borrowing" our conventional graphical labels from the surrounding
context. Tufte feels the context will be enough to provide for effective
interpretation.

Again there are issues of aspect ratio. A sparkline is constrained in
that it is word-like---meaning broader than they are tall. In time
series data, Cleveland's Law says the slope should be around 45 degrees
to better reveal the action in the data.

To describe a digital time series, such as won-lost records in baseball,
another type of sparkline can be used. Like this:

Orioles ![](media/image2.png){width="1.2361111111111112in"
height="0.18055555555555555in"} 7-25

Using "whiskers" set along the top (for wins) and bottom (for losses) of
an X-axis, trends can be quantitatively assessed at a glance in a way
that conveys far more meaning than a word or phrase. Here again we see
several axes of information, including wins and losses; home games, as
indicated by the thin horizontal line along the X-axis, and away games,
indicated by no horizontal line; and shut outs, indicated by red
whiskers.

Note, morey disturbance is maximized when the white space-to-whisker
size is one-to-one. So be careful to avoid visual vibration, either by
thinning the whisker lines or graying the lines just a bit. Currently,
you need three computer applications to do sparklines: (1) a statistical
package (i.e., Excel), (2) a drawing program (i.e., Adobe Illustrator)
and (3) a layout program (i.e., Quark Express). (There are 14 more pages
on this topic on Tufte's Web site, at
http://www.edwardtufte.com/tufte/index)

Tufte noted the map on page 80 of his book *Envisioning Information*.
The topographical contour lines are different colors in different
locations. This was done deliberately to avoid visual vibration. He
found this effective.

**The Cognitive Style of PowerPoint**

Tufte said Microsoft PowerPoint (and all programs like it) is entirely
presenter oriented, not content oriented and not audience oriented.
PowerPoint foreshortens evidence and thought. It is a tool that is
inherently low in spatial resolution. PowerPoint constrains users to a
hierarchical, single-path structure of communication, while often
disrupting the flow of the narrative.

The attitude in the design of PowerPoint is as follow: "What counts are
power and pitches, not truth and evidence," says Tufte. This is contrary
to science. *Resolution is a measure of intellectual progress.* Reducing
resolution, on the other hand, is a measure of intellectual retardation.
By analogy, the average PowerPoint contains 2% to 10% of the typographic
richness of nonfiction bestsellers.

Try never to attract attention to your method of presentation, rather
you should endeavor to attract attention to your *content*. The
presentation should be transparent and indifferent, endlessly
self-effacing.

**Use Handouts *in lieu* of PowerPoints**

A handout in a meeting allows people to read and think about your
subject, even when you're talking about something else. So what?
*They're your words!* The point is your audience is still reading and
thinking about your topic. Moreover, effectively designed handouts will
preclude boring questions and, instead, will more likely prompt incisive
questions about *why* something was done. Tufte said he'd be happy to
just be in the room with us while we all read his books that he gave us,
asking questions as needed.

Give people the evidence and let them reason about the material. Let it
be interactive, and let it not be static and one-way.

**Visual Explanations** (see p. 30)

It is very important to put individual names on individual works. This
lends identity and credibility, showing that someone is willing to stand
behind their work. On this note, Tufte shared some lessons learned from
the Challenger shuttle accident, which led him to produce the following
list of demands an audience rightfully makes of a presenter:

1\. [Show me causality]{.underline}. Nearly every serious decision
demands a causal idea.

2\. [Show me all relevant data]{.underline}. When you ask for all
relevant data, you eliminate or minimize the ability for selective
presentation of data (potentially precluding bias, whether inadvertent
or deliberate). Evidence must support theory of causality.

3\. [What do I really need to know?]{.underline} Ask yourself, what
would Richard Feynman do? (Tufte cited Feynman a number of times during
his lecture. He clearly admires Feynman as a "clear thinker.")
Presenters should demonstrate research structure and method for evidence
gathering.

Tufte said this list of demands comes with a guarantee that there is no
better method. This is essential in the processes of science and
engineering, and should be ingrained into the process.

**How to Make A Presentation**

#1 - Show up early to your own presentation. About 1 time in 20 you can
head off a serious problem by showing up early. When people come to
meetings they tend to trickle in. You can be there to greet, give
handouts, and advance your cause. Conversely, the rudest thing a
presenter can do to his audience is come in late.

#2 -- A good idea right up front is to tell people what the problem is,
what the relevance is, and your proposed solution. As a side note, Tufte
recounted the "stumble bum" technique once used by a high school teacher
giving a lecture in mathematics to a room full of college math
professors. The high school teacher began with a confession of "not
being an expert on the subject," and then proceeded to write a proof on
the board in which he made a mistake. Members of his audience quickly
leaned forward and pointed out his error. He thanked them and proceeded
with the remainder of his talk. And as he proceeded, he made no more
mistakes. But the audience was leaning forward, hanging on every word
and looking for his next mistake. He effectively captured and held their
undivided attention! (Be careful, this tactic is not for the meek or
faint of heart.)

#3 -- To explain something complicated, try PGP: Particular, General,
Particular. First give a specific example or data point, then place the
example or data within context, and then give another example.

#4 -- No matter what, give everyone in the audience a piece of paper. It
is the highest resolution means of information transfer at your
disposal.

#5 -- You can think about your audience by what they read.

#6 -- {Oops, sorry. I missed this. I suffer from attention deficit
disorder.}

#7 -- Audiences are precious and you should not ever waste their time.
NEVER underestimate your audience. Avoid the adage: "KISS -- Keep It
Simple Stupid," which is itself stupid and condescending to your
audience. Speak to your audience respectfully and with a reasonable
level of frankness. Rather than "Know your audience," Tufte advocates:
"Know your *content* and *respect* your audience." Presentations should
be content driven, not design driven.

#8 -- Humor is helpful and makes things memorable and can communicate a
kind of attitude and spirit. BUT BE CAREFUL. Often set jokes fail and
cause embarrassment. People are quick to take offense and so be careful
not to accidentally alienate your audience with some joke that can be
misinterpreted. If you are going to risk offending your audience, do so
gratuitously only on the merits of your content.

#9 -- Avoid gratuitous use of vague pronouns. *It* can be hard enough
for *them* to understand without *those* getting in the way.

#10 -- You should not give your presentation behind a "bullet proof"
podium, w/ your hands clutching the sides. This will influence your
affect. Your audience wants to see your body language and watch you
demonstrate through gesture, etc. Conversely, a podium blocking your
body language and direct interactions with your audience could
negatively enhance the credibility of your presentation.

#11 -- Finish early. No one ever leaves a meeting and says, "Gee, I wish
that had gone on another 20 minutes."

**Some additional notes for outside the meeting:**

1\. Practice, practice, practice! Rehearsal improves performance. If you
have a friend from whom you can take criticism, use him/her. Or try your
presentation in front of a camera. It won't lie.

When you look at something, look at it at its normal size and an order
of magnitude larger and smaller. So turn those principles toward how you
view a video of your own talk. Watch it at normal speed, then in slow
motion, and then at high speed. There may be rhythmic patterns you
weren't aware of. Next, turn off the picture and listen to the audio.
Avoid repetitive use of such words as "actually" or "basically" or
"significantly." And, um, try not to, uh, say "um" or "uh." (Most talks
Tufte has seen began with the word "um.")

2\. Be aware that your talk will stand or fall on the quality,
credibility, and relevance of its *content*.