Presenting Visual Data la Edward Tufte

1
Presenting Visual Data à la Edward Tufte

• Marvin Miller, M.D.
• August 6, 2008

2
Objectives

• Participants will
• improve their graphical presentations
• be able to more critically evaluate the graphical
  presentations of others
• identify the limitations and shortcomings of
  PowerPoint presentations

Thank you Erin Ash Patricia Hudes
3
Who is Ed Tufte?

• The maven on how to effectively present
  information - especially statistical and
  quantitative information
• Professor Emeritus at Yale
• Prolific writer
• Founder Graphics Press
• Courses throughout USA
• Galileo of Graphics
• da Vinci of Data

4
Tufte Course October 5, 2006 Cincinnati

• Enlightening and entertaining
• Information rich
• PROVOCATIVE
• Extremely helpful in improving my own activities
  of information presentation
• Allowed me to apply basic principles to the
  evaluation of presentations of others

5
Tuftes 4 Books
6
Topics Explored

• History
• Music
• Art
• Medicine
• Stock Market
• Birds
• Astronomy

• Fish
• Architecture
• Sports
• Magic
• Genetics
• Cancer
• Space Flight

7
Spiritually Moving Experience

• To witness original books of Galileo
• making a presentation is a moral act as well -
  Beautiful Evidence, page 9
• Well reasoned and honest presentations have the
  potential to be life saving poorly reasoned or
  dishonest presentations can be life harming

8
Tufte on Galileo
9
William Playfair (1759-1823)
The inventor of most of the common graphical
forms used to display data the scatterplot, line
plots, bar chart and pie chart.

• His The Commercial and Political Atlas, published
  in 1786, contained a number of interesting
  time-series charts such as these.

10
Excellence in statistical graphicsCommunicating
complex ideas with

• Clarity
• Precision
• Efficiency

The Visual Display of Quantitative Information -
Ed Tufte 2nd edition, page 13
11
Escaping the Flatland

• We should make things as simple as possible,
  but not simpler."
• - Albert Einstein

"We envision information in order to reason
about, communicate, document, and preserve that
knowledge -- activities nearly always carried out
on two-dimensional paper and computer screen.
Escaping this flatland and enriching the density
of data displays are the essential tasks of
information design. - Edward R. Tufte,
Envisioning Information
12
Graphical Display Should

• Show the data
• Induce the viewer think about substance
• Avoid distorting what the data have to say
• Present many numbers in a small space
• Make large data sets coherent

• Encourage the eye to compare different pieces of
  data
• Reveal the data at several levels of detail
• Serve a reasonably clear purpose description,
  exploration, tabulation, or decoration
• Be closely integrated with the statistical and
  verbal description of the data set

The Visual Display of Quantitative Information -
Ed Tufte 2nd edition, page 13
13
Tufte's Grand Principles of Design

• show comparisons
• show causality
• show more than 1 or 2 variables
• integrate word knowledge and image
• document everything and tell your audience
  about it
• presentation stands or falls on the quality,
  integrity, and relevance of the content
• show your information at once, adjacent in
  space, rather than stacked in time

14
The single biggest threat to learning the truth
from a presentation is "cherry picking" data.
15
Anscombes Quartet

• For all 4 sets of data
• N 11 (x,y) pairs
• Mean of Xs 9.0
• Mean of Ys 7.5

• Equation of regression line
• Y30.5X

16
Anscombes Quartet
17
The Nobel Prize to Brown and Goldstein for
describing Familial Hypercholesterolemia came
about because they appreciated the significance
of the high cholesterol outliers
Distribution of Serum Cholesterol
Controls
Myocardial infarction survivors
18
Statistics are like a bikini what they reveal is
suggestive, but what they conceal is vital.
19
Cholera EpidemicLondon 1854
Dr. John Snow
20
Tufte's nomination for one of the best graphics
ever producedCharles Minard's Graph of
Napoleon's Invasion of Russia
21
New York Citys Weather for 1980
1,888 numbers that tell a story
22
Good Example Cancer Rates
23
Good Example Genealogy of Pop Rock Music
24
Good Example SARS
25
Good Example
Comparative Chromosomes

• from L to R
• Man
• Chimpanzee
• Gorilla
• Orangutan

26
If you could upgrade one aspect of your computer
system, what part of your system would you choose
to improve upon or enhance in capacity?
27
Data Density
Data density ( of entries in data
matrix)/(area of graphic)

• Note that low data densities on computer displays
  force us to view information sequentially, rather
  than spatially, which is bad for comprehension.
• Good quality graphics are
• Comparative
• Multivariate
• High density
• Able to reveal interactions, comparisons, etc
• And where nearly all of the ink is actual data ink

28
Tufte's first three principles for displaying
information

• Above all else, show the data
• Maximize the data-ink ratio
• Erase non-data ink

29
Data-Ink

• Data-ink ratio
• data-ink
• total ink used to print the graphic

• Maximize the data-ink ratio, within reason
• Erase non-data ink, within reason

30
Maximize Data/Ink Ratio
The labeled, shaded bar chart displays the height
in six ways

• the height of the left line,
• the height of the right line,
• the height of the shaded region,
• the position of the horizontal bar,
• the position of the number above the bar, and
  finally
• the number itself.

31
Information Dense
32
Aspect Ratio
The aspect ratio is vital because it has a large
impact on our ability to judge rate of change. A
number of studies in visual perception have
shown that our ability to judge the relative
slopes of line segments on a graph is maximized
when the absolute values of the orientations of
the segments are centered on 45 degrees. -
Cleveland
33
Sparklines in Medical Care
34
Sparkline in Medical Care
35
Sparklines in Finances
36
Sparklines in Sports
37
Pie Chart An Inferior Choice for Graphical
Display of Information
Estimation of U.S. Population as Percent of World
Population, January 2002 (source US Census)
38
Pie Chart versus Table
Item 1 5
Item 5 57
Item 2 89
Item 4 87
Item 3 27
39
Dragons of Eden
Sagan
versus
Tufte
40
Edward Tufte, The Cognitive Style of PowerPoint
41
Tuftes Criticism of PowerPoint Presentations

• Elevates format over content
• LOW information density
• Information is stacked in time
• For school children, hinders the writing of
  meaningful sentences
• Stifles information design creativity

42
Cancer Rates by Site, 1973-2003

• Consider an important and intriguing table of
  survival rates for those with cancer relative to
  those without cancer for the same time period.
  Some 196 numbers and 57 words describe survival
  rates and their standard errors for 24 cancers.

43
Applying the PowerPoint templates to this nice,
straightforward table yields an analytical
disaster. The data explodes into six separate
chaotic slides, consuming 2.9 times the area of
the table. Everything is wrong with these
smarmy, incoherent graphs the encoded legends,
the meaningless color, the logo-type branding.

• They are uncomparative, indifferent to content
  and evidence, and so
• data-starved as to be almost pointless.
  Chartjunk is a clear sign of statistical
  stupidity. Poking a finger into the eye of
  thought, these data graphics would turn into a
  nasty travesty if used for a serious purpose,
  such as helping cancer patients assess their
  survival chances. To sell a product that messes
  up data with such systematic intensity, Microsoft
  abandons any pretense of statistical integrity
  and reasoning.

44
(No Transcript)
45
Avoid Chartjunk

• The interior decoration of graphics generates a
  lot of ink that does not tell the viewer anything
  new. The purpose of decoration varies to make
  the graphic appear more scientific and precise,
  to enliven the display, to give the designer an
  opportunity to exercise artistic skills.
  Regardless of its cause, it is all non-data-ink
  or redundant data-ink, and it is often
  chartjunk. - Ed Tufte

46
(No Transcript)
47
(No Transcript)
48
Grand Rounds and PowerPointSocratic Dialogue
Gives Way to PowerPointLawrence AltmanNew
York Times, December 12, 2006

• Grand rounds are not so grand anymore
• .and the Socratic dialogue has given way to
  PowerPoint.

49
Evolution of Medicine
PATIENT CARE
Written Narrative
EMR
TEACHING
Patient Focused
Powerpoint
1970
2010
2000
50
Challenger O Ring Damage
History of O-Ring Damage in Field Joints
51
How the Data Could Have Been Presented
52
Tufte Tips for Oral Presentations

• At beginning of talk, tell audience
• What the problem is
• Why the problem is important
• What the solution to the problem is
• Know your content
• Practice, practice, practice
• Show up early something good will happen
• Give a written handout (Word not PowerPoint)
• Get out from behind podium Be demonstrative
• Never apologize
• Finish early

53
Escaping the flatland is the essential task of
envisioning information for all the interesting
worlds (physical, biological, imaginary, human)
that we seek to understand are invariably and
happily multivariate in nature - Ed Tufte
54
Good design is clear thinking made visibleBad
design is stupidity made visible
www.edwardtufte.com