InfoVis

Question 1

What is the difference between nominal data and ordinal data?

Answer 1

Nominal data is data with “labels”.

Ordinal data is data which has a natural order of the values

Question 2

What does it mean to roll up/drill down in a visualisation?

Answer 2

Drill-down refers to the process of viewing data at a level of increased detail, while roll-up refers to the process of viewing data with decreasing detail.

Question 3

Describe the Exploratory Process

Answer 3

1 Construct graphics to address questions
2 Inspect “answer” and assess new questions
3 Repeat!

Question 4

what are the Nominal operations?

Answer 4

= , !=

Question 5

what are the Ordinal operations? (ordered)

Answer 5

=, !=, >,

Question 6

what are the Quantitative

operations? (interval)

Answer 6

=, !=, >,

Question 7

what are the Quantitative

operations? (ratio)

Answer 7

=, !=, >,

Question 8

List 4 important Vis Design Considerations

Answer 8

Avoid unexpressive marks
Don’t distract:
Support comparison and pattern perception
Group / sort data by meaningful dimensions
Transform data
Reduce cognitive overhead
Minimize visual search, minimize ambiguity

Question 9

Radar Plot / Star Graph

Answer 9

“Parallel” dimensions in polar coordinate space

Best if same units apply to each axis

Question 10

Scatterplot Matrix

Answer 10

Good for seeing correlations in pairs of
dimensions
…however they’re positioned,
unlike Parallel Coords

Question 11

Single Plot Visualisation

Answer 11

Create single scatterplot showing overall structure of data

Compare objects: rows of the spreadsheet
Treat inter-object similarity as high-dimensional distance

Find a low-dimensional layout that retains as much of the relative distances between objects as possible
Similar objects close together in the layout, and dissimilar objs far apart

Question 12

Force-based models

Answer 12

Simulated systems of objects with position,
velocity, forces, mass…

a rough analogy with mechanical spring systems, the
gravitational systems of planets, etc. …but simplified so as to be coded more easily and to run more quickly

Question 13

What are Strategies for Visualising Multiple Dimensions

Answer 13

• Start by visualising individual dimensions
• Avoid “over-encoding”
• Use space and small multiples intelligently
• Use interaction to generate relevant views

There is rarely a single visualisation that answers all
questions. Instead, the ability to generate
appropriate visualisations quickly is key

Question 14

give the ‘just noticeable difference’ formula

Answer 14

(delta)S = k (delta i /i)

Question 15

What is Steven’s power law?

Answer 15

Stevens’ power law is a proposed relationship between the magnitude of a physical stimulus and its perceived intensity or strength.

Question 16

Give a rough ordering of the accuracy of different methods of represening magnitudes

Answer 16

position
length
slope
angle
area
volume
colour/hue

Question 17

What is pre-attentive processing?

Answer 17

Preattentive processing of visual information is performed automatically on the entire visual field detecting basic features of objects in the display. Such basic features include colors, closure, line ends, contrast, tilt, curvature and size.