MELJUN CORTES research seminar_1_presentation_techniques

1. Presentation Techniques
Presenting Your Data Easily

2. Why Worry About Graphics?
“Data graphics are mainly devices for
showing the obvious to the ignorant”
“They have to be alive, communicatively
dynamic, decorated, and exaggerated;
otherwise all the dullards will fall asleep in
the face of those boring statistics”
Graphics are instruments for reasoning
about quantitative information… They
reveal data.” (Tufte 1983)

3. Principles of Graphic Excellence
Graphical excellence…..
consists of complex ideas communicated
with clarity, precision, and efficiency.
is that which gives to the viewer the
greatest number of ideas in the shortest
time with the least ink in the smallest space.
is nearly always multivariate (illuminating
relationships between numerous variables)
requires telling the truth about the data

4. Some Rules of Thumb
Graphic displays should…..
show the data
avoid distorting the data
induce the viewer to think about the substance
of the graphic rather than the methodology,
graphic design, or something else
make large amounts of data coherent
encourage the viewer to use the graphic as you
intend, e.g. make comparisons
be closely integrated with statistical and verbal
descriptions of the data
be as simple as possible

5. Design Guidelines
To enhance visual quality:
use a properly chosen format
use words, numbers, and graphics
together
display an accessible complexity of detail
have a story to tell about the data
produce technical details with care
avoid chartjunk

6. Effective Communication
“You can communicate more effectively with tables,
graphs, or charts, if your {information has} these
characteristics” (Booth et al. 1995):
They include discrete elements (cases) that are well
defined, well understood, and stable - persons, places,
things, or concepts.
The discrete element is an ‘independent’ variable,
that does not change in response to other variables.
The discrete elements are systematically related to
quantities or qualities, called dependent variables,
that do not change in response to external causes.

7. Tabular Presentation
“An informative table supplements rather than
duplicates - the text.” (APA 1994)
Tables “are the best way to show exact numerical
values and are preferable to graphics for many
small data sets {of about 20 numbers or less}.”
(Tufte 1983)

9. State of Florida Household Income,
1999
Taken from the US Census Bureau Website

10. The Tabular Superhero:
Supertables
Tables also work well when the data presentation
requires many localized comparisons, i.e. a
supertable
Supertables are large tables made up of many
different component tables that summarize
relationships across the same variable(s)

13. Rules of Thumb for Good Tables
Tables need a comprehensive and descriptive title
(Variable, Geography, Time)
Bay County Percent Population by Race, 2000
Right justify numbers in tables
Use commas to delineate thousands
Use numeric signs to signpost the table viewer
(percent signs (%), dollar signs ($), etc.)
Always use the same number of decimal places
Use gridlines to separate table elements
Use italics and bold to identify column headings

14. Variations in County Poverty Rates, 1999
County Percent
Poverty
County
A
11.12%
County
B
22.00%
County
C
8.50%
County
D
43.79%
Source: 2000 Census
County Percent
Poverty
County A 11.12
County B 22
County C 8.4967
County 43.8
Poverty Rates
“Good Table” Example
--Good Title
--Nice presentation
--Numeric formatting
--Bold, Italics
--Gridlines
--Sourcing
“Bad Table” Example
--Poor Title
--Confusing presentation
--No source

15. Choosing Formats: Charts/Graphs
“Figures convey at a quick glance an overall
pattern of results.”
They are especially useful in describing an
interaction - or the lack thereof - and nonlinear
relations.” (APA 1994)

16. Bar Charts and Graphs
Bar charts / graphs (histograms) are typically
used when the independent variables are
categorical variables [Nominal Variables]
They are also useful for showing changes over
time as well (although line charts are often a better
choice to show these relationships).

18. Taken from the Tallahassee Statistical Digest, 2001

19. Pie Charts
Pie charts are used to illustrate percentages or
proportions of a whole. They are par5ticularly
useful in investigating discrete elements of:
-Populations
-Budgets
But “at best, they allow readers to see crude
proportions among a few elements.” (Booth et al.
1995)

21. Line Graphs
Scatter plots and line graphs are used to show
the relation between two quantitative variables
where there is a unique value of the dependent
variable for any value of the independent variable
The independent variable is typically plotted on
the x axis while the dependent variable is plotted
on the y axis
Line graphs are especially effective at presenting
data that vary continuously

22. Source: US
Census

24. Complex Graphs:
Combination Charts
There are times when you want to present two or
more variables in the same chart.
Combination charts allow the user to combine
two different variables in the same chart in order to
illustrate the relationships between these variables.
The choice of presentation method is dictated by
the variables and the nature of the relationship
between the variables.

25. Source: US
Census
Clustered Column Chart
Example

26. Source: Tallahassee 2003 CIP
Clustered Bar Chart
Example

27. Stacked Column Chart
Example

28. Line-Column Chart
Example

29. Four Broad Principals of
Data Presentation (from Myers)
Integration: Tables and graphics should be part of a “seamless information
flow”. Text should refer to and direct readers towards these exhibits.
Speed and Efficiency of Communication: Exhibits should be clearly and simply
presented, well-titled, and linked to the purpose of the report/memo; The
goal is efficiency of communication.
Engagement in Depth: The longer the viewer spends with an exhibit, the more
they should get out of it. “The goal is to create a richly informative exhibit
that is dense with information, but open and accessible to the eye.”
Trustworthiness: Exhibits present factual information. They must be supported
with appropriate sourcing and with all information presented correctly and
understandably.

30. Presentation Reminder for
Tables and Charts
1) Give ALL tables and figures titles and numbers.
2) No “Hanging Tables and Figures”: Refer to any and all
tables in a report/memo.
3) Source all Tables and Charts
4) Provide a good title for all Tables and Charts (Variable,
Geography, Time)
5) If you want a reader to compare two charts, show
them on the same page.
6) If you want a reader to compare two charts, use similar
colors, titles, labels, fonts, and so on. The only major
difference should be the data.

31. Misleading the Unwashed Masses
While very powerful, graphics are potentially
dangerous because they can easily mislead decision
makers and the public at large.
Because graphics are often slick and attractive
elements, they can lead viewers to assume certain
things about them:
1) That graphics are accurate (truthful) and that
data used to make the graphics are accurate.
2) They are neutral (objective) data displays that
do not present any point-of-view in their display.

32. A Graphical Caveat
“A single map is but one of an indefinitely large
number of maps that might be produced for the same
situation or the same data.”
Monmonier, How to Lie with Maps, p. 2
The maker of a graphic (maps and chart, especially) has
tremendous power over the product and the consumer.
This power can be used to create effective, attractive
graphics that competently and truthfully convey
information or graphics that unfairly distort reality and
(un)intentionally mislead the audience.

33. Graphical Deceit?
If you were running for Mayor in Capital City, which
graphic
would you use to illustrate your success?

34. The St. Joe
Perspective
The Riverkeepers
Perspective