CSC 465 Quizzes

Third most effective visual encoding for perceptual effectiveness?

Area

Good for categorical X values and cases where the Y value is ratio scaled.

Bar Chart

A violin plot with data plotted as dots within the 'violin' area is called (notable because this is what Tableau does for violin plots)

Bean Plot

Second most effective visual encoding for perceptual effectiveness?

Length/distance with no common baseline

Which of the following are potential problems using circles on maps to show data at locations

Areas of circles are not a strong data encoding for fine comparison Common circle pitfall - must encode area not radius! Correct Answer Correct Response Overplotting - too many circles makes the map context impossible to read

TreeMaps are an example of which type of visualization

Bubble chart & Space-filling visualization

Carefully consructed to match human perception of color

CIE-Lab

When graphical integrity is compromised, a graph can be misleading (intentionally or by accident). Watch out for:

Changing the Y axis to make the data fit tightly. Scaling the area used to represent a data point when only the length should be scaled. Changing the X axis so that aggregation in different scales can be misleading

4th most effective visual encoding for perceptual effectiveness?

Color

One criteria for making sure the data are the most prominent feature of a visualization is the

Data to ink ratio

Used for variables that have values with two separate extremes and neutral ground in between.

Divergent

Tableau allows you to create new visualizations by:

Dragging and dropping variables onto the axes and Selecting variables and choosing a recommended 'Show Me' graph.

Which of these are true about node-link layouts of hierarchical data (multiselect)

Drawing the deepest part of the tree it is easy to run out of space. The angle in a circular hierarchical graph is encoding the structure, as opposed to just some data value. Using a radial layout gives more space for the deeper nodes.

Implies some importance of the connection between the data points.

Line Graph

One critical attribute of good data visualization is that data themselves are emphasized. One way to make the data stand out is to:

Remove clutter.

The Earth is flat

False

A very common example of a hierarchical visualization in everyday computer usage is:

File system / folder browser

Which color is most strongly perceived by your brain

Green

Moving from the tip of the cone that contains all values of this color space, straight through to the bottom means transitioning from black to white.

HSN

One alternative to a treemap when there hare only a couple levels of depth is to use a (hint: Tableau lets you switch between this easily)

Hierarchical bar chart

Which of the following are types of smoothing used to show patterns in timeseries data

LOESS (small regression to see the trend in the immediate area of each point) moving average (average of a time window surrounding each point) weighted moving-average (average of a time window surrounding each point, with more recent points stronger)

Order the visual encoding (aka mappings) in terms of their effectiveness. Which encoding is the most effective?

Length/distance with a common baseline

Maps only to variables of a nominal type, i.e. not continuous. It gets cluttered and confusing to use too big a palette (too many colors) at a time.

Qualitative

Red, Green and Blue are points on a 3D cube.

RGB

Can handle multiple Y values per X value

Scatter Plot

Used for common continuous variables that vary from low to high.

Sequential

Suppose the values for some variable X are in the range 10 million to 100 million dollars. Using the axis label "Log of Dollars" vs. "Log of Millions of Dollars" means

Shifting the scale by an offset

A Tukey Box Plot can be used to show values with uncertainty, i.e. sampled from a distribution. Besides showing the median, it shows context by indicating

The outliers plotted as points & One quartile on either side of the median.

To create contrast when choosing two colors, pick them

from opposite sides of the color wheel

According to Weber's Law, perception is not simply on absolute terms, but

We perceive differences as a function of the magnitude of the original (i.e. we perceive percentage changes)

When hierarchical data is represented in a table:

When hierarchical data is represented in a table:

An exponential function f(x) is one of the form:

a*n^x

Incrementally builds graphs by allowing you to add on to a baseline piece by piece

ggplot

One usage of Panel Plots is to show data that would otherwise be a dense set of timeseries lines. Panel Plots

break the lines out into separate pieces can be (unacceptably) confusing/misleading if the axis range are not the same across panels

The Quantile-Quantile (Q-Q) Plot

can make a comparison between two distributions. plots the values of two different variables in order.

A map in which the areas of landmasses are morphed to match with some data characteristic is called a

cartogram

A map where individual area segments are colored to correspond to data values is called a

chloropleth

A cholorpleth is also an example of a

heatmap

Single function call takes a bunch of options at once and produces a graph in one shot

qplot