Visual Analytics & Design Introduction

Question 1

What is InfoVis?

Answer 1

It is a process of transforming information into a visual form enabling the viewer to observe, browse, make sense, and understand the information.

Question 2

In InfoVis what is shown?

Answer 2

Data Abstraction

Question 3

In InfoVis why is the user looking at it?

Answer 3

Task Abstraction

Question 4

In InfoVis how is it shown?

Answer 4

Idiom: visual encoding and interaction

Question 5

What can be visualized?

Answer 5

To answer this questions:

What dataset?

What types of data?

Question 6

Why people are using vis in terms of actions and targets?

Answer 6

To answer this questions:

What tasks?

What purpose?

Question 7

How to design vis idioms: encode, manipulate, facet, and reduce?

Answer 7

Techniques used to visually encode data.

Question 8

What are the four levels of Design in InfoVis?

Answer 8

• Domain situation
• Data/task abstraction
• Visual encoding/interaction idiom
• Algorithm

Question 9

What is the domain level?

Answer 9

The users

Their questions

The vocabulary

The data

Question 10

What is the abstraction level?

Answer 10

Abstract into domain independent vocabulary.

Appears different in the problem domain, actually same task.

Question 11

What is the idiom level?

Answer 11

Create the visual representation.

Question 12

What is the algorithm level?

Answer 12

How to actually get it done!

Question 13

What are the two “Angles of Attack”?

Answer 13

• Problem-driven
• Technique-driven

Question 14

What is Problem-driven?

Answer 14

Top-Down

Have a question, want to have a good way of answering it.

Question 15

What is Technique-driven?

Answer 15

Bottom-Up

Want to develop a new algorithm.

No idiom seems to work for the tasks at hand.

Question 16

What are the five basic data entities?

Answer 16

• Items
• Attributes
• Links
• Positions
• Grids

Question 17

What is the first aspect to consider when designing a problem-driven visualization?

Answer 17

With problem-driven work, you start at the top domain situation level and work your way down through abstraction, idiom, and algorithm decisions.

Question 18

There are four different types of search actions in information visualization. What are they and when do they take place, depending on the nature of data?

Answer 18

• Lookup: find it where you expect it.
  ex: locate yourself on your family tree.
• Browse: know where it is, but not what it is.
  ex: who were my great-grandfather’s brother’s sons?
• Locate: I know what, but not where.
  ex: how is Paul related to me in the family tree?
• Explore: look for interesting things.
  ex: who were my ancestors? How did they relate to one another?

Question 19

What is the best channel to encode a quantitative variable: position or angle? Why?

Answer 19

Position.

The attributes encoded with position will dominate the user’s mental model — their internal mental representation used for thinking and reasoning — compared with those encoded with any other visual channel.

Question 20

Color consists of different components. Color hue, in particular, is more correctly used to encode attributes of a particular type. Name this attribute type and discuss the reason why this rule must be followed.

Answer 20

Identity Channels: Categorical Attributes.

The major design choice for color-map construction is whether the intent is to distinguish between categorical attributes or to encode ordered attributes.

Question 21

John needs to create a visualization to use in his neuroscience research to study brain cortex areas and their functions in mice. He asked his friends for help but they don’t seem to agree. While Mary argues that 3D should be avoided at all costs when creating an effective visualization, Joseph believes that it is the best option in this case. With whom do you agree and why?

Answer 21

If we have a need for visualization in clinical context and in a situation where we need to analyze three dimensional models, the 3D option is certainly better as it will also have to be production information in this case (eg: cuts, slices, etc…).

Question 22

What is the Pre-Attentive Processing (“Popout”)?

Answer 22

Low-level tasks that can be accomplished almost instantaneously (<250msec) without focused attention. Objects seem to “pop-out”.

Question 23

What is a mark?

Answer 23

The visual element (line, star, bar, wedge, etc.).

Question 24

What is a channel?

Answer 24

The visual property (length, size, shape, etc.).

Question 25

When to do not use bar charts?

Answer 25

Do not use bar charts for time series.

Question 26

When to do not use line charts?

Answer 26

Do not use line charts for comparison across categories.

Question 27

Where lines are better?

Answer 27

Lines: Better for trends.

Question 28

Where areas are better?

Answer 28

Areas: Better for totals.

Question 29

Point out three ways in which the following chart is misleading us:

Answer 29

1) Wrong scale, the first value could be zero or something more relevant (burried bar);
2) Bar chart in 3D not easy to compare;
3) Depft makes it difficult to tell each bar’s value;

Question 30

Consider the following dataset.

Indicate, for each attribute, what is its type?

Answer 30

name - Nominal

population - Ratio

capital - Nominal

fun - Ordinal

Year of foundation - Quantitative