Data Visualization Color Theory and Visual Encoding 3 — Questions and Answers
Question 1: What is 'data-ink ratio' as defined by Edward Tufte?
- The ratio of colored ink to black ink
- The proportion of ink devoted to displaying non-redundant data (Correct answer)
- The ratio of chart area to whitespace
- The number of colors used per data point
Correct answer: The proportion of ink devoted to displaying non-redundant data
Tufte's data-ink ratio is the fraction of ink used to represent actual data versus total ink used; maximizing it reduces chart junk.
Question 2: What is 'chartjunk' according to Edward Tufte?
- Low-quality data
- Unnecessary visual elements that do not convey information (Correct answer)
- Overly complex datasets
- Charts created with poor software
Correct answer: Unnecessary visual elements that do not convey information
Chartjunk refers to decorative or redundant visual elements—gridlines, 3D effects, clipart—that clutter charts without adding informational value.
Question 3: Which principle suggests that visual elements encoding the same variable should be perceptually uniform?
- Gestalt principle
- Perceptual linearity (Correct answer)
- Color harmony
- Tukey's ladder
Correct answer: Perceptual linearity
Perceptual linearity ensures that equal data differences appear as equal visual differences (e.g., perceptually uniform color scales like viridis).
Question 4: What visual encoding principle states that elements close together are perceived as belonging to the same group?
- Similarity
- Closure
- Proximity (Correct answer)
- Continuity
Correct answer: Proximity
The Gestalt principle of proximity states that spatially close elements are automatically perceived as grouped together.
Question 5: Why should pie charts avoid using more than 5–6 slices?
- Software limitations
- Humans struggle to accurately compare small angles and thin slices (Correct answer)
- Colors run out
- Labels overlap on large slices
Correct answer: Humans struggle to accurately compare small angles and thin slices
Humans are poor at judging small angle differences, making thin pie slices nearly impossible to compare accurately.
Question 6: Which of the following best describes the 'lie factor' in data visualization?
- The number of false data points in a chart
- The ratio of visual effect size to actual data effect size (Correct answer)
- The percentage of missing data
- The distortion caused by 3D perspective
Correct answer: The ratio of visual effect size to actual data effect size
Tufte's lie factor = size of effect shown in graphic ÷ size of effect in data; values other than 1.0 indicate misleading graphics.
Data Visualization Color Theory and Visual Encoding 3
What is 'data-ink ratio' as defined by Edward Tufte?