Data Visualization SeminarNCDC, April 27 2011

Todd Pierce

Module 1 Data Visualization

Introduction

    

This seminar will look at visualization from the viewpoint of human perception and cognition

How do humans perceive and use visuals? What are some principles that can be applied to visualizations to make them more effective?

The seminar is a summary of the first half of the UNC Asheville class “Tools for Climate Data and Decision-Making”

Outline

    

1 Data Visualization – history, uses, good and bad visuals

2 Human Perception – visual attendance, patterns, and working memory

3 The Eightfold Way – principles for effective visualizations

Lunch break4 Best Practices – color, parts of a graph, picking the

correct graph5 Types of Graphs – types of analysis supported, do’s

and don’t’s6 Maps – (if time allows)

THEORY

PRACTICE

Sources

    

Sources

    

Sources

    

Let’s Get Started

    

Facebook Friends Graph

http://www.facebook.com/notes/facebook-engineering/visualizing-friendships/469716398919

Need for Climate Change Communication

    

Why are the skills in this course important?

- Climate Data needs to be a part of decision making as humans must start enacting climate mitigation and climate adaptation programs

- Climate Data is overwhelming in its quantity and needs to be better presented in visualizations – maps, charts, graphs – that can be used in decision making

Need for Climate Change Communication

    

According to Global Climate Change Impacts in the United States

-Global warming is unequivocal and primarily human-induced

-Climate changes are underway in the US and are projected to grow

-Widespread climate-related impacts are occurring now and are expected to increase

-Future climate change and its impacts depend on choices made today

Need for Climate Change Communication

    

Despite the need for choices to be made now, climate change skepticism abounds

http://environment.yale.edu/uploads/SixAmericasJan2010.pdf

Need for Climate Change Communication

    

There is a need to counteract the skeptics, but how? Climate Change is not a sound bite – it has complex concepts and counterintuitive findings as well as mountains of data.

Some examples…

Need for Climate Change Communication

    

Skeptics vs Scientific Consensushttp://www.informationisbeautiful.net/visualizations/climate-change-deniers-vs-the-consensus/

Increasing Sea Levelshttp://www.informationisbeautiful.net/visualizations/when-sea-levels-attack/

Need for Climate Change Communication

    

Moscow Summer Heat Wave 2010http://www.climatecentral.org/gallery/graphics/

how_unusual_was_the_russian_heat_wave_of_2010/

Need for Climate Change Communication

    

Increased US Snowhttp://www.climatecentral.org/gallery/graphics/arctic-paradox-warmer-

arctic-may-mean-colder-winters-for-some/

Data Visualization

So…data visualization can help explain climate change data (as well as many other things)

Let’s look at data visualization

why use it?when did it get started?

what makes a good or bad visualization?

Why Use Visualizations?

To explain and to persuade

“picture is worth a thousand words”

Visuals help meet several objectives

Why Use Visualizations?

Objectives for Visuals-Clarity: make technical or numerical data easier

to understand-Simplification: break down narrative

description into smaller parts (flow chart)-Emphasis: draw attention to certain facts-Summarization: show conclusions or main

points

Why Use Visualizations?

Objectives for Visuals-Reinforcement: complement text and use

repetition to help remember idea-Interest: break up blocks of text-Impact: grab reader’s attention and keep it-Credibility: impress reader with data validity

(“pictures don’t lie” ?)-Coherence: help show how related parts of a

document work together

Definition

Data visualization: the visual representations that support the exploration, examination, and communication of data.

• Information visualization: abstract data

• Scientific visualization: physical data, such as through X rays or MRI scans

History

• Tables date to 2nd century CE, first ones in Egypt for astronomical data for navigation

• Descartes created the Cartesian graph in the 17th century, but for mathematical analysis, not for information visualization

source: Stephen Few

History

• In late 18th/early 19th century, William Playfair created or improved graphs for use in information visualization – invented the bar graph, used line graphs to show time trends, and invented the pie chart.

source: Stephen Few

History

• First college course in graphs in 1913 at Iowa State – today few courses offered outside of statistics classes

• John Tukey in 1977 started exploratory data analysis as a tool for statistics – invented tools such as the box plot to help show trends in data and prove power of visualization for data exploration

source: Stephen Few

History

• Edward Tufte in 1983 published The Visual Display of Quantitative Information, the first book to really show effective and beautiful ways existed to show data, and that most visuals did not use them

source: Stephen Few

History

• In 1984 the Apple Macintosh debuted – the first affordable PC with a graphical interface

• William Cleveland in 1985 published The Elements of Graphic Data – expanded on Tukey and improved use of visualization in statistics

source: Stephen Few

History

• The National Science Foundation started efforts in scientific visualization in 1986

• By 1999, information visualization was recognized as distinct discipline within visualization in general

• Two conditions needed for modern information visualization: – graphical computers– lots of readily accessible data. – Before, data was limited to the printed page, which can only

be physically manipulated – the data is locked on the page and can’t be changed. With computers, users can interact with the data and explore ways to show it.

What Makes a Good Visual?

Easy to understandCombines multiple data sourcesTells a storyEncourages aha! MomentsLeads to new insights and predictionsOften used in unrelated areas

“forces us to notice what we never expected to see” – J W Tukey

What Makes a Good Visual?Easy to understand

What Makes a Good Visual?Easy to understand

What Makes a Good Visual?Combines multiple data sources

What Makes a Good Visual?Combines multiple data sources

What Makes a Good Visual?Tells a story

What Makes a Good Visual?Encourages aha! moments

What Makes a Good Visual?

What Makes a Good Visual?Leads to new insights and predictions

What Makes a Good Visual?Leads to new insights and predictions

What Makes a Good Visual?Often used in unrelated areas

What Makes a Good Visual?Often used in unrelated areas

What Makes a Good Visual?Often used in unrelated areas

What Makes a Good Visual?Often used in unrelated areas

What Makes a Good Visual?Often used in unrelated areas

What Makes a Good Visual?Often used in unrelated areas

What Makes a Bad Visual?

Misleading or wrongIgnores contextUglyConfusingObscures message

With computers, it is very easy to make a bad chart, graph, or map

What Makes a Bad Visual?Misleading or wrong (perspective issues)

What Makes a Bad Visual?Misleading or wrong (area used for linear value)

What Makes a Bad Visual?Misleading or wrong

What Makes a Bad Visual?Misleading or wrong

What Makes a Bad Visual?Misleading or wrong

What Makes a Bad Visual?Misleading or wrong – track removed

What Makes a Bad Visual?Misleading or wrong

What Makes a Bad Visual?Ignores context

What Makes a Bad Visual?Ignores context

What Makes a Bad Visual?Ugly (“chart junk”)

What Makes a Bad Visual?Confusing

What Makes a Bad Visual?Obscures message

What Makes a Bad Visual?Obscures message – better version

Next Module: Human Perception

    

How can we make visuals better, so they show more of the ‘good’ qualities and less of the ‘bad’ qualities?

We can consider principles of human perception.