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Lec 6 Data Visualization

The document discusses the importance of data visualization as a means to represent information graphically, enabling quick interpretation and insight extraction from large datasets. It emphasizes understanding visual perception principles, such as Gestalt psychology, to design effective visualizations that enhance cognitive processing and reduce cognitive load. The content also highlights the role of visual attributes in effectively communicating data and the necessity of evaluating visualization effectiveness.

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0% found this document useful (0 votes)
72 views101 pages

Lec 6 Data Visualization

The document discusses the importance of data visualization as a means to represent information graphically, enabling quick interpretation and insight extraction from large datasets. It emphasizes understanding visual perception principles, such as Gestalt psychology, to design effective visualizations that enhance cognitive processing and reduce cognitive load. The content also highlights the role of visual attributes in effectively communicating data and the necessity of evaluating visualization effectiveness.

Uploaded by

Syed Ahad
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Big Data Analytics

Data Visualization
Motivation
Visual Perception
Eye Vs. Camera
Gestalt Principles
Context, Preattention, Magnitude Estimation
Visual Attributes and Visual Mapping
Evaluating Visualization
Effectiveness, Expressiveness, Integrity, Consistency
Chart Junk

Imdad ullah Khan

Imdad ullah Khan (LUMS) Data Visualization 1 / 101


Data Visualization

Data Visualization is the graphical representation of information and data.


Visual elements like charts, graphs, and maps, provide an accessible way
to see trends, outliers, and patterns in data

Enables the quick interpretation of data


Helps communicate information clearly and efficiently
Essential for data-driven decision making

The primary goal of data visualization is not only to present data but to
provide insights that are not immediately obvious through raw data.

Efficiency: Rapidly digest large amounts of data


Pattern Recognition: Identify patterns, relationships, and outliers
Storytelling: Translate findings into a narrative to influence
decision-making

Imdad ullah Khan (LUMS) Data Visualization 2 / 101


Data Visualization

What information consumes is rather obvious: it consumes the attention


of its recipients. Hence a wealth of information creates a poverty of
attention, and a need to allocate that attention efficiently among the
overabundance of information sources that might consume it.
Herb Simon, Scientific American, 1995

Data volume and velocity is much higher than our ability to draw
knowledge from it
Visualization helps draw knowledge form data (beyond statistical
inference)
Visualization reveal information that statistics may not
Visualization of scientific data magnifies the capabilities of science to
understand the universe

Imdad ullah Khan (LUMS) Data Visualization 3 / 101


Data Visualization: Why?

Imdad ullah Khan (LUMS) Data Visualization 4 / 101


Data Visualization: Why?

Bathymetric map
Nautical Chart
Reveal Hidden dangers
Helps marine navigation

Imdad ullah Khan (LUMS) Data Visualization 5 / 101


Data Visualization: Why?
Popular belief in 1850: cholera spreads via airborne transmission
Dr. John Snow plotted each death on a London map
Noticed clusters around a certain contaminated well

Steve Marschner @Cornell

Imdad ullah Khan (LUMS) Data Visualization 6 / 101


Data Visualization: Why?
Popular belief in 1850: cholera spreads via airborne transmission
Dr. John Snow plotted each death on a London map
Noticed clusters around a certain contaminated well

images source: https://www.theguardian.com/news/datablog/2013/mar/15/john-snow-cholera-map

Imdad ullah Khan (LUMS) Data Visualization 7 / 101


Data Visualization: Why?

States mean income and fraction of college degree holders

source: Bradley Hemminger, Uni. of North Carolina

Which state has the largest and the smallest —?


Which states are outliers if any?
How is income related to college degree?
Imdad ullah Khan (LUMS) Data Visualization 8 / 101
Data Visualization: Why?
Can easily tell what is largest/smallest in every dimension

Imdad ullah Khan (LUMS) Data Visualization 9 / 101


Data Visualization: Why?
Visualization helps identify relationship easily as compared to raw data

Imdad ullah Khan (LUMS) Data Visualization 10 / 101


Data Visualization: Why?
Outliers stand out and get identified easily

Imdad ullah Khan (LUMS) Data Visualization 11 / 101


Data Visualization: Why?

Anscombe’s Quartet: Four datasets with identical statistics

x 4 5 6 7 8 9 10 11 12 13 14
y 4.26 5.68 7.24 4.82 6.95 8.81 8.04 8.33 10.84 7.58 9.96

x 4 5 6 7 8 9 10 11 12 13 14
y 3.1 4.74 6.13 7.26 8.14 8.77 9.14 9.26 9.13 8.74 8.1

x 10 8 13 9 11 14 6 4 12 7 5
y 5.39 5.73 6.08 6.42 6.77 7.11 7.46 7.81 8.15 12.74 8.84

x 8 8 8 8 8 8 8 8 8 8 19
y 6.58 5.76 7.71 8.84 8.47 7.04 5.25 5.56 7.91 6.89 12.5

µx = 9 σx = 3.316 µy = 7.500 σy = 2.031

▷ Edward Tufte, The visual display of quantitative information

Imdad ullah Khan (LUMS) Data Visualization 12 / 101


Data Visualization: Why?

Anscombe’s Quartet: 4 datasets with identical regression line

Imdad ullah Khan (LUMS) Data Visualization 13 / 101


Data Visualization: Why?

The eye and the visual cortex of the brain form a massively parallel processor
that provides the highest-bandwidth channel into human cognitive centers.
Colin Ware, Information Visualization, 2004

Visual system is the highest bandwidth channel to the brain


70% of body’s sense receptors reside in our eyes
Metaphors to describe understanding often refer to vision (“I see,”
“insight,” “illumination”) ▷ Thinking with our Eyes
Need an efficient way to understand Big Data

Imdad ullah Khan (LUMS) Data Visualization 14 / 101


Data Visualization: Why?

Makes the vast amounts of data more comprehensible


Reveals invisible parts in data that we don’t have access to otherwise
Analyze things that are otherwise difficult
Allows for quick decisions based on real-time data visualizations
Capture events
See things at a level that is not available at our own perception
Magnifies our ability to understand things better
Help us tell a story
Visualizations transcend language barriers and are universally
understandable

Imdad ullah Khan (LUMS) Data Visualization 15 / 101


Visual Perception

Imdad ullah Khan (LUMS) Data Visualization 16 / 101


Visual Perception

Understanding how we perceive visual information is crucial for designing


effective data visualizations
Knowing how the brain would read visualization enhances design
▷ Know your audience
Understanding mechanisms of the visual processing system and using that
knowledge can result in improved displays
Having an idea of human perception and psychology helps in optimal
visual mapping and developing meaningful visualization

Imdad ullah Khan (LUMS) Data Visualization 17 / 101


The Visual Processing System

The human visual system is a complex mechanism evolved to process


information efficiently and effectively.

Eye as a Sensor: Captures light and transmits signals to the brain


Visual Cortex: Processes visual information to interpret shapes,
colors, and patterns
Cognitive Processing: Uses stored knowledge and context to make
sense of visual data

Imdad ullah Khan (LUMS) Data Visualization 18 / 101


Visual Perception: Eye vs Camera
Camera:
Good optics
Single focus, white balance, exposure
Full image capture source: researchpedia.info

Eye:
Poor optics
Constantly scanning (saccades)
Constantly adjusting focus
Constantly adapting white balance,
exposure
Mental reconstruction of image (sort of) source: quora.com

Imdad ullah Khan (LUMS) Data Visualization 19 / 101


Visual Perception: Eye vs Camera

Visual Perception is not just camera work

Which square between A and B is darker?


Imdad ullah Khan (LUMS) Data Visualization 20 / 101
Visual Perception: Eye vs Camera

Visual Perception is not just camera work

Both have the same darkness!


Imdad ullah Khan (LUMS) Data Visualization 21 / 101
Visual Perception: Eye vs Camera

Visual Perception is not just camera work

Color is relative

Imdad ullah Khan (LUMS) Data Visualization 22 / 101


Visual Perception: Gestalt Principles

Gestalt Psychology

The human mind considers objects in their entirety before,


or in parallel with, perception of their individual parts;
suggesting the whole is other than the sum of its parts.
Theory of Perception - wikipedia

Gestalt Psychology provides valuable insights into how people perceive


visual components as whole forms rather than just as simple sums of parts
Proximity: Elements close to each other are perceived as a group
Similarity: Items that are similar are grouped together
Continuity: Eyes are drawn along paths, lines, and curves
Closure: We perceive whole shapes even when parts are missing
Anomaly: The mind is very good at identifying outliers
Imdad ullah Khan (LUMS) Data Visualization 23 / 101
Visual Perception: Gestalt Principles

Similarity: The mind perceives similar shapes in a relationship and bring


them together to form larger shapes

How many circles and squares are there?

Imdad ullah Khan (LUMS) Data Visualization 24 / 101


Visual Perception: Gestalt Principles

Anomaly: The mind is very good at identifying outliers

Which piece stands out?

Imdad ullah Khan (LUMS) Data Visualization 25 / 101


Visual Perception: Gestalt Principles

Continuation: The mind finds meaning in continuation in shapes that are


next to each other

Did the leaf come out of the H? Did the “lions” scare the birds?

Imdad ullah Khan (LUMS) Data Visualization 26 / 101


Visual Perception: Gestalt Principles

Closure: The mind makes shapes contiguous

How many triangles? Where is the top of the panda?

Imdad ullah Khan (LUMS) Data Visualization 27 / 101


Visual Perception: Gestalt Principles

Proximity: The mind perceive closer things as related

Is there any big square?

Imdad ullah Khan (LUMS) Data Visualization 28 / 101


Visual Perception: Gestalt Principles

Imdad ullah Khan (LUMS) Data Visualization 29 / 101


Visual Perception: Context

Context: Context can change the appearance of same object

image credit: John Hart, UIUC

Both lines are equal?

Imdad ullah Khan (LUMS) Data Visualization 30 / 101


Visual Perception: Context

Context: Context can change the appearance of same object

image credit: John Hart, UIUC

Which line looks longer?

Imdad ullah Khan (LUMS) Data Visualization 31 / 101


Visual Perception: Context

Context: Context can change the appearance of same object

image credit: John Hart, UIUC

Is the difference more significant?

Imdad ullah Khan (LUMS) Data Visualization 32 / 101


Visual Perception: Context

Context: Context can change the appearance of same object

image credit: John Hart, UIUC

Imdad ullah Khan (LUMS) Data Visualization 33 / 101


Visual Perception: Context

Context: Context can change the appearance of same object

image credit: John Hart, UIUC

Imdad ullah Khan (LUMS) Data Visualization 34 / 101


Visual Perception: Preattention

Preattention: Some visual features are detected immediately

Pop-out vs. Serial Search


If recognition takes 200 − 250ms, then it qualifies as preattentive
eye movements takes > 200ms, yet some processing can be done
quickly
If a decision takes a fixed amount regardless of the number of
distraction, it is considered to be preattentive
It is important for effective visualization to use better discrimination
and avoid misleading viewers

Imdad ullah Khan (LUMS) Data Visualization 35 / 101


Visual Perception: Preattention

Preattention: Some visual features are detected immediately

How many 5’s are there?

385720939823728196837293827
382912358383492730122894839
909020102032893759273091428
938309762965817431869241024

Imdad ullah Khan (LUMS) Data Visualization 36 / 101


Visual Perception: Preattention

Preattention: Some visual features are detected immediately

How many 5’s are there?

385720939823728196837293827
382912358383492730122894839
909020102032893759273091428
938309762965817431869241024

Imdad ullah Khan (LUMS) Data Visualization 37 / 101


Visual Perception: Preattention

Preattention: Color (hue) is preattentive

Detect red circle among these circles

Imdad ullah Khan (LUMS) Data Visualization 38 / 101


Visual Perception: Preattention

Preattention: Form (curvature) is (somewhat) preattentive

Detect red circle among the following objects

Imdad ullah Khan (LUMS) Data Visualization 39 / 101


Visual Perception: Preattention

Preattention: Conjunction of attributes is generally not preattentive

Detect red circle among blue circles and red squares

Imdad ullah Khan (LUMS) Data Visualization 40 / 101


Visual Perception: Preattention

Preattention: Detecting slanted line among vertical lines is preattentive

Imdad ullah Khan (LUMS) Data Visualization 41 / 101


Visual Perception: Selective Attention

Selective Visual Attention: Visual processing confined to certain stimuli

Watch the video of 6 players passing basketballs among themselves


3 players wearing black and 3 wearing white shirts
You should answer with two integers
Counts of the number of aerial and bounced passes between white
shirted players
http://viscog.beckman.uiuc.edu/grafs/demos/15.html

Imdad ullah Khan (LUMS) Data Visualization 42 / 101


Visual Perception: Magnitude Estimation

How much bigger is the bigger circle?

Imdad ullah Khan (LUMS) Data Visualization 43 / 101


Visual Perception: Magnitude Estimation

How much bigger is the bigger bar?

Imdad ullah Khan (LUMS) Data Visualization 44 / 101


Visual Perception: Magnitude Estimation

How much bigger?

Imdad ullah Khan (LUMS) Data Visualization 45 / 101


Visual Perception: Magnitude Estimation

Steven’s Power Law

Heuristics for perceptual estimation

Length is estimated within factors of [.9 − 1.1]


Area is estimated within factors of [.6 − .9]
Volume is estimated within factors of [.5 − .8]

Imdad ullah Khan (LUMS) Data Visualization 46 / 101


Cognitive Load and Information Processing

Effective visualizations reduce cognitive load—making it easier for the


brain to process and understand information.

Intrinsic Load: Complexity inherent in the data itself


Extraneous Load: Complexity added by the way information is
presented
Germane Load: Cognitive effort to process and understand
information

Applying principles of perception and cognition to visualization design


enhances the effectiveness and clarity of visual data representation.

Using color to highlight differences in data points effectively reduces


cognitive load by drawing attention to key elements without overwhelming
the viewer.

Imdad ullah Khan (LUMS) Data Visualization 47 / 101


Basic Principles of Data Visualization

Imdad ullah Khan (LUMS) Data Visualization 48 / 101


Basic Principles of Data Visualization

Understanding the fundamental principles of data visualization is crucial


for creating effective and meaningful visualization
These principles ensure that visualizations are not only appealing but also
functional and informative.

Clarity: The visualization should convey the intended message in a


clear and concise manner
Accuracy: Representations must be precise and accurate to maintain
data integrity
Efficiency: Information should be presented in the most efficient way
possible, without unnecessary complexity
Aesthetics: Visually appealing presentations can engage the
audience more effectively

Imdad ullah Khan (LUMS) Data Visualization 49 / 101


Visualization Principles: Clarity

Clarity is about making the data easy to read and understand. The goal is
to simplify the presentation so that the audience can grasp it quickly
without confusion

Example of Clarity
A bar chart showing sales data over months should have clear labels, a
legible font size, and distinct colors for different products to facilitate easy
understanding.

Imdad ullah Khan (LUMS) Data Visualization 50 / 101


Visualization Principles: Accuracy

Accuracy ensures that the visual representation faithfully reflects the data.
Misleading visuals can lead to incorrect conclusions and decisions

Example of Accuracy
A pie chart representing market share should correctly depict proportions.
Any rounding errors or scaling mismatches can lead to misinterpretation of
the competitive landscape.

Imdad ullah Khan (LUMS) Data Visualization 51 / 101


Visualization Principles: Efficiency

Efficient visualizations convey information quickly and directly, using the


least amount of graphical elements necessary to communicate the message
effectively

Example of Efficiency
A line graph showing trends over time is more efficient than a detailed
table as it allows the viewer to quickly ascertain directional changes and
patterns.

Imdad ullah Khan (LUMS) Data Visualization 52 / 101


Visualization Principles: Efficiency

While functionality is critical, aesthetics play an important role in making


visualizations pleasing to engage with, which can enhance viewer
interaction and retention

Example of Aesthetics
Using a harmonious color scheme and balanced layout in a dashboard can
make the data not only more appealing but also easier to navigate and
interpret.

Imdad ullah Khan (LUMS) Data Visualization 53 / 101


Visual Mapping or Visual Encoding

Imdad ullah Khan (LUMS) Data Visualization 54 / 101


Visual Mapping

Understanding different data types and their appropriate visualization


techniques is essential for effective data representation.

Mapping data attributes to visual attributes


Pick the best mapping
Visually encode different data types for maximum impact and clarity
Consider importance Ordering
Encode the most important information in the most perceptually
accurate way

Imdad ullah Khan (LUMS) Data Visualization 55 / 101


Visual Mapping: Data Types

Imdad ullah Khan (LUMS) Data Visualization 56 / 101


Visual Attributes or Visual Variables

Position
Length
Area
Volume
Shape
Color
Angle
Slope
Texture

Imdad ullah Khan (LUMS) Data Visualization 57 / 101


Relative Magnitude Estimation of Visual Variables

More Accurate

Position
Length
Area
Volume
Shape
Color
Angle
Slope
Texture
Least Accurate

Imdad ullah Khan (LUMS) Data Visualization 58 / 101


Visual Mapping for Data Types

Bertin’s Visual Mapping, Level of Organization

Visual attribute Suitable target data attributes

Position N O Q
Size N O Q
Value N O Q

Texture N O
Color N
Orientation N
Shape N
Imdad ullah Khan (LUMS) Data Visualization 59 / 101
Visual Mapping for Data Types

Mackinlay ranking of attributes by visualization efficacy

Imdad ullah Khan (LUMS) Data Visualization 60 / 101


Visual Mapping: Color Encoding

Imdad ullah Khan (LUMS) Data Visualization 61 / 101


Guidelines for colors

Use only a few colors


Colors should be distinctive and named
Strive for color harmony
Beware of cultural conventions
Beware of bad interactions
Get it right in black and white

Imdad ullah Khan (LUMS) Data Visualization 62 / 101


Evaluating Visualization

Imdad ullah Khan (LUMS) Data Visualization 63 / 101


Evaluating Visualization

Goal of data visualization:

Communicate information clearly and efficiently to users via statistical


graphics, plots, information graphics tables and charts

Effective data visualization is not just about displaying data but doing so
in a way that is accurate, clear, and ethical

These are the criteria to evaluate visualizations

Effectiveness
Expressiveness
Integrity
Consistency

Imdad ullah Khan (LUMS) Data Visualization 64 / 101


Evaluating Visualization: Effectiveness

Effectiveness
A visualization is more effective than another visualization if
the information conveyed by one visualization is more readily
perceived than the information in the other visualization.
Mackinlay, 1986

Keep the design simple and the message clear

Imdad ullah Khan (LUMS) Data Visualization 65 / 101


Effectiveness - Purpose of Visual

Identify purpose of visual - to compare values, show trends, explore


distribution or relationship between variables - choose visual accordingly

https://towardsdatascience.com/tips-for-effective-data-visualization-d4b2af91db37

Imdad ullah Khan (LUMS) Data Visualization 66 / 101


Effectiveness - Focus on Vital Data Points

Vital Data Points are few: Which visual gives better insight of sudden dip?

https://towardsdatascience.com/tips-for-effective-data-visualization-d4b2af91db37

Imdad ullah Khan (LUMS) Data Visualization 67 / 101


Effectiveness - Suppress the Noise

Make the noise less pronounced

https://towardsdatascience.com/tips-for-effective-data-visualization-d4b2af91db37

Imdad ullah Khan (LUMS) Data Visualization 68 / 101


Effectiveness - Use Colors Wisely

Should the same thing be represented with different colors?

https://towardsdatascience.com/tips-for-effective-data-visualization-d4b2af91db37

Imdad ullah Khan (LUMS) Data Visualization 69 / 101


Effectiveness - Avoid Unnecessary Aesthetic Sense

Box Plot with too much aesthetics sense (using too much ink)

Imdad ullah Khan (LUMS) Data Visualization 70 / 101


Effectiveness - Avoid Unnecessary Aesthetic Sense

Scale shifted to side

Imdad ullah Khan (LUMS) Data Visualization 71 / 101


Effectiveness - Avoid Unnecessary Aesthetic Sense

Upper boundaries removed

Imdad ullah Khan (LUMS) Data Visualization 72 / 101


Effectiveness - Avoid Unnecessary Aesthetic Sense

More effective representation

Imdad ullah Khan (LUMS) Data Visualization 73 / 101


Effectiveness - Avoid Unnecessary Aesthetic Sense

Right brightness

Imdad ullah Khan (LUMS) Data Visualization 74 / 101


Effectiveness - Avoid Unnecessary Aesthetic Sense

The following plots have exactly the same information but huge difference
in ink use

https://towardsdatascience.com/tips-for-effective-data-visualization-d4b2af91db37

Imdad ullah Khan (LUMS) Data Visualization 75 / 101


Evaluating Visualization: Expressiveness

Expressiveness
A set of facts is expressible in a visual language if the
sentences (i.e. the visualization) in the language express all
the facts in the set of data and only the facts in the data.
Mackinlay, 1986

Imdad ullah Khan (LUMS) Data Visualization 76 / 101


Evaluating Visualization: Expressiveness

Lengths (interpreted as quantitative values) express non-facts

Imdad ullah Khan (LUMS) Data Visualization 77 / 101


Evaluating Visualization: Expressiveness

Lengths (interpreted as quantitative values) express non-facts

Imdad ullah Khan (LUMS) Data Visualization 78 / 101


Evaluating Visualization: Integrity

Integrity
What is presented should accurately represents what is in
the data being visualized, and that no design choices should
distort or obfuscate the facts and analytical findings

Ensure all visual elements accurately represent the underlying data

Imdad ullah Khan (LUMS) Data Visualization 79 / 101


Evaluating Visualization: Tufte’s Principles of Integrity

1 The representation of numbers, as physically measured on the surface of the


graphic itself, should be directly proportional to the numerical quantities
measured

2 Clear, detailed, and thorough labeling should be used to defeat graphical


distortion and ambiguity. Write out explanations of the data on the graphic
itself. Label important events in the data
3 Show data variation, not design variation

4 In time-series displays of money, deflated and standardized units of


monetary measurement are nearly always better than nominal units
5 The number of information-carrying (variable) dimensions depicted should
not exceed the number of dimensions in the data
6 Graphics must not quote data out of context

Imdad ullah Khan (LUMS) Data Visualization 80 / 101


Evaluating Visualization: Integrity

Students Gender Distribution

https://towardsdatascience.com/tips-for-effective-data-visualization-d4b2af91db37

Imdad ullah Khan (LUMS) Data Visualization 81 / 101


Evaluating Visualization: Integrity

Imdad ullah Khan (LUMS) Data Visualization 82 / 101


Evaluating Visualization: Integrity

Imdad ullah Khan (LUMS) Data Visualization 83 / 101


Evaluating Visualization: Integrity

Distorted x-axis for rise in global warming

Imdad ullah Khan (LUMS) Data Visualization 84 / 101


Evaluating Visualization: Integrity

Yield of a process increased from 56% to 67% over a period of 6 months

Which visual is exaggerating the increase?

Imdad ullah Khan (LUMS) Data Visualization 85 / 101


Evaluating Visualization: Integrity

American election expenditures

Which visual is exaggerating the increase in expenses from 1972 to 1982?

http://www.astro.caltech.edu/ay119/bdass/davidoff-3-viscommfund.pdf

Imdad ullah Khan (LUMS) Data Visualization 86 / 101


Evaluating Visualization: Integrity

Properties of visualization should match the properties of data

Two-dimensional data mapped with three-dimensional representation

Imdad ullah Khan (LUMS) Data Visualization 87 / 101


Evaluating Visualization: Consistency

Consistency: mainly apply to sets of visualizations


Effectiveness and expressiveness ask for optimal visual encoding and space
used in one visual
Individually optimized (locally effective) but not globally consistent visuals
can be misleading

Use consistent styles and colors to avoid confusing the viewer


The same fields should be presented in the same way
Different fields should be presented in different ways

Imdad ullah Khan (LUMS) Data Visualization 88 / 101


Evaluating Visualization: Consistency

Qu & Hullman (2016) Evaluating Visualization Sets:


Trade-offs Between Local Effectiveness and Global Consistency

Imdad ullah Khan (LUMS) Data Visualization 89 / 101


Evaluating Visualization: Consistency

Qu & Hullman (2016) Evaluating Visualization Sets:


Trade-offs Between Local Effectiveness and Global Consistency

Imdad ullah Khan (LUMS) Data Visualization 90 / 101


Evaluating Visualization: Chart Junk

Maximal Data:Ink Rato


A sentence should contain no unnecessary words, a paragraph no
unnecessary sentences, for the same reason that a drawing should
have no unnecessary lines and a machine no unnecessary parts.
William Strunk, Jr.

Do not try to deceive the audience - Avoid manipulating visual


mapping to exaggerate findings
Avoid 3D - visually appealing, but 3D can distort data interpretation
Keep chart junk to minimum to prevent distractions
Minimize use of Ink
Some chart junk helps in remembering though
Excessive use of colors can be distracting and misleading

Imdad ullah Khan (LUMS) Data Visualization 91 / 101


Evaluating Visualization: Chart Junk

Avoid chart junk, if it does not add any value

http://jcsites.juniata.edu/faculty/rhodes/ida/graphicalIntRedes.html

Imdad ullah Khan (LUMS) Data Visualization 92 / 101


Evaluating Visualization: Chart Junk

Avoid chart junk, if it does not add any value

Imdad ullah Khan (LUMS) Data Visualization 93 / 101


Evaluating Visualization: Chart Junk

Avoid chart junk, if it does not add any value

Imdad ullah Khan (LUMS) Data Visualization 94 / 101


The Grid System
Grid system naturally organizes data to give it more meaning

Imdad ullah Khan (LUMS) Data Visualization 95 / 101


The Grid System

Which news is more important? Which is more visible?

Imdad ullah Khan (LUMS) Data Visualization 96 / 101


The Grid System

Grouping of elements in columns has a certain meaning

Imdad ullah Khan (LUMS) Data Visualization 97 / 101


Data Visualization Process

From data to insight, the visualization process involves several key steps:

1 Data Collection: Gathering the necessary data from various sources


2 Data Cleaning: Preparing the data by cleaning and structuring it
3 Data Analysis: Analyzing the data to find patterns and insights
4 Data Visualization: Representing the data visually to highlight
findings
5 Insight Communication: Using the visualization to tell a story or
support decision-making

Imdad ullah Khan (LUMS) Data Visualization 98 / 101


Data Visualization Process: Purpose

Purpose of your visualization

Are you exploring the data?


Are your formatting it for decision making?
Or are you telling a story?

Imdad ullah Khan (LUMS) Data Visualization 99 / 101


Data Visualization Process: Principles

Eight Principles of communicating through data

Define what questions are you answering


Use accurate data
Experiment with ways to answer
Go with cognitive research (go with the rules defined through
previous research for data visualization)
Faithfully represent your data
Tailor it to your audience
Make it as simple as possible
Remove everything that you can

Imdad ullah Khan (LUMS) Data Visualization 100 / 101


Data Visualization Process

1 Choosing the visualization for your purpose


Simple numbers? pie charts? bar charts? Tables? plots? maps?

2 Choosing right tool and coding language


Excel, tableau, Microsoft power BI, illustration software
R, Python etc.

Imdad ullah Khan (LUMS) Data Visualization 101 / 101

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