Unit 2 Flashcards
Theory II
Which of the following enables analog perception?
Encoding BMI as the height of bars on a bar chart
What is a major problem with using the HSV color model for information visualization?
It is not perceptually uniform - Yes, creating HSV hues that vary in value by a fixed interval will result in a set of hues that we do not perceive with equal interval changes
Suppose you want to use color to encode BMI (Body Mass Index) on glyphs, such that it is possible for a person to use color to see how far or close each glyph is to the population average for BMI, including whether the value is higher or lower than normal. This is best done using a
Diverging palette of two hues where the first hue varies from dark (lower than normal) to white (normal), and the second hue varies from white (normal) to dark (higher than normal)
The color palette used to encode each clinic in the charts (stacked bar chart, grouped bar chart, line plot) is an example of
a palette of distinct hues
In the HSV model, how are these colors different?
[from darkest red - almost black - to lightest red]
Value - value refers to the amount of light falling on a hue. Here the light goes from none to high.
Select the most accurate statement about preattentive attributes
- preattentive attributes require no attention
- all preattentive attributes are equally strong
- a single feature map contains a number of different preattentive attributes
**preattentive attributes vary in strength **
The most accurate perception of differences across years for clinic 2 is possible in the [ (stacked bar chart, grouped bar chart, line plot)]
Grouped bar chart and Line plot :
These two charts are both good for accurately perceiving change over time for clinic 2. The grouped bar chart suffers a bit because the other clinic’s bars separate those for clinic 2 making it a bit difficult to compare just the bars for clinic 2. The line chart is typically the best chart for comparing change over time and detecting trends, but both the line and bar are equal with respect to accuracy–both use vertical distance from a common baseline.
The most accurate perception of differences in proportions for a single year is possible in the grouped bar chart and line plot, but not the stacked bar chart, because
Length of lines with common baselines and 2D positions with common baselines are the most accurate to compare perceptually
In a parallel visual search, the time to find a target is
independent of the number of distractors
Following the proximity-compatibility principle, if users need to compare values, such as profits from three different companies over time, these values would best be shown in
the same graph -
Putting all companies on the same line chart graph permits accurate comparison of difference in each year and across years, including trends.
Labeling bars or charts directly, instead of using colors and then having a separate key that lists the colors and labels, is an example of
In the HSV model, how are these colors changing?
[ from light red pinkish to darker bold red]
Saturation
