Designing Better Graphs

transcript

Matthew Wettergreen, PhD

Components of a Good Graph

● Proper data organization (MOST IMPORTANT)● Formatted without default settings● Designed for ease of readability for others

● Correct use of “preattentive stimulus”● Visual Hierarchy● Readable text● Properly formatted axes● Properly weighted lines● Appropriate color (only when necessary)

Identifying the Proper Format for Your Data:What Relationships are you trying to Show?

Relationship Example Question

RankIn what order are our proposed device designs based on the summed values from the Pugh matrix from high to low?

Part-to-whole

What portion of the market does our company command, and how does that compare to our competitors?

Time-series Is the traffic on our website increasing or decreasing?

DeviationTo what degree do our device’s readings vary relative to the expected numbers?

Distribution

What is the range of our employees’ salaries, and how many employees fall into each subset of that range in increments of $10,000?

Correlation

Is there a relationship between the stiffness of our construction material on the strength of our constructed shape?

Do Not Use Program Defaults!

● Thin lines

● Too small of text

● Box around data

● Often lacks labels

● Grey background

● Gridlines

● Bad colors

● Boxes around everything

Pre-attentive Processing

extremely fast, pre-conscious visual processing

How many 5’s are in this figure?

385720939823728196837293827

382912358383492730122894839

909020102032893759273091428

938309762965817431869241024

How many 5’s are in this figure?

385720939823728196837293827

382912358383492730122894839

909020102032893759273091428

938309762965817431869241024

Preattentive Processing

• There are some basic visual properties that can be detected immediately by low-level visual system

• These are identified from a “Pop-out” instead of a “Serial Search”

• Preattentive Processing relates to tasks that can be performed in less than 200 to 250 milliseconds on a complex display

Color (hue) is preattentive

Detection of red circle in group of blue circles is preattentive

Form (curvature) is preattentive

Curved form “pops out” of display

Don't Over Do It!Conjunction of Attributes

Conjunction targets generally cannot be detected preattentively

The red circle hides in the sea of red square and blue circle

Other Preattentive Examples

Which Preattentive Stimulus is Best for Quantitative/Qualitative Data?

Type Attribute Quantitatively Perceived?

Form Line Length Yes

Line width Yes, limited

Orientation No

Size Yes, limited

Shape No

Curvature No

Added Marks No

Enclosure No

Color Hue No

Intensity Yes, limited

Position 2-D Position Yes

Preattentive Stimuli has a Visual Heirarchy

Which preattentive stimulus is stronger?

Visual Hierarchy

Highlighting Trends Using Sorting

• Sorting and rearranging data lets users visually draw meaningful comparisons from the data

• Sort based on the relationship and pattern you are trying to flush out in this graph, not by convention (ie alphabetically)

Before After

Visual Hierarchy for Text

Amount of Sales by Salesperson

Dodsworth Suyama Davolio Fuller Peacock Leverling Arcoll Callahan Dusty

Salesperson

Graph Text Must Have a Consistent Visual Hierarchy

The visual hierarchy of this graph is inconsistent

Visual Hierarchy of Text

Actual

Amount of Sales ($)

2500, 2000, 1500, 1000, 500, 0

Dodsworth, Suyama, Davolio, Fuller, Peacock, Leverling, Arcoll, Callahan, Dusty

Salesperson

Correct

Title (1st)

X-Axis Title (2nd)

Y-Axis Title (2nd)

X-Axis Data (3rd)

Y-Axis Data (3rd)

Data Labels (4th)

Choosing a Readable Font

Fine Legibility Poor Legibility

Serif San-Serif Serif San-Serif

Times New Roman Arial Script Gill Sans ITC

Palatino Verdana Broadway Papyrus

Courier Tahoma Old English Tempus Sans ITC

Dodsworth Suyama Davolio Fuller Peacock Leverling Arcoll Callahan Dusty

Salesperson

The visual hierarchy of this graph has been fixedand is now consistent

Properly Formatting Axes

Formatting of Axes• Scaling and aspect ratio of your axes is important to

bring out the relevant relationships and patterns

• Axes should have consistent labeling – no interval jumps

• Breaks in axes should be clearly indicated

Don't Do

Use a Correct Y-Axis Range

Don't Do

Select the Correct Aspect Ratio

Don't Do

Properly Formatted Lines

• Use reference lines (grids) only when an important values should be seen across an entire graph

• Tick marks should generally face outward

• Don’t clutter the interior of the scale-line rectangle with legends, labels, and lines

Grid Lines Can Obscure Data

Don't Do

Proper Use of Color

Color Choices

• Use color only to serve a specific communication goal

• Use more than one color only when the data means different things

• Use a mix of soft colors for the data and brighter colors to accentuate specific features

This is What Bad Color Use Looks Like

Quantitative Use of Color

● Color is mostly arbitrary, that is, non-directional● The human eye cannot perceive quantitative

differences in hue or color

What do the different shades of green mean in reference to the red?

Color Perception Can Be Tricked

All five of these grey boxes are the same shade

Use one color per series

Color Palette Examples

Standard palette for data

For accentuating features and trends

Use Hues to Order Data

Some Rules About Using Color

● To speed visual search

● To improve object recognition

● To enhance meaning

● To convey structure

● To establish identity

● To … symbolism

● To improve usability

● To communicate mood

● To show associations

● To express metaphors

Components of a Good Graph

●Proper data organization (MOST IMPORTANT)●Formatted without default settings●Designed for ease of readability for others

● Correct use of “preattentive stimulus”● Visual Hierarchy● Readable text● Properly formatted axes● Properly weighted lines● Appropriate color (only when necessary)

Resources for Better Graphs

● Chart Chooser– Extreme Presentation: Chart Suggestions

● http://extremepresentation.typepad.com/files/choosing-a-good-chart-09.pdf

– Juice Analytics: Chart Chooser● http://labs.juiceanalytics.com/chartchooser.html

● Color– Color Scheme Designer

● http://colorschemedesigner.com/

Designing Better Graphs

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