Data Science Data Visualization and Communication 3 — Questions and Answers
Question 1: Which chart is best for showing a trend in a continuous metric over time?
- Pie chart
- Line chart (Correct answer)
- Treemap
- Heatmap
Correct answer: Line chart
Line charts connect ordered time points to clearly show trends and direction over time.
Question 2: A stakeholder says your dashboard is 'too busy.' Which action most directly addresses this?
- Add more KPIs to each panel
- Reduce clutter and highlight only the most relevant metrics (Correct answer)
- Increase color saturation everywhere
- Add animated transitions
Correct answer: Reduce clutter and highlight only the most relevant metrics
Simplifying and focusing on key metrics reduces cognitive load and improves clarity.
Question 3: Which encoding is generally perceived most accurately by the human eye (per Cleveland & McGill)?
- Color hue
- Area
- Position along a common scale (Correct answer)
- Volume
Correct answer: Position along a common scale
Position along a common scale is the most accurately perceived visual encoding for quantitative values.
Question 4: What is the primary risk of using a dual-axis chart with two different y-scales?
- It cannot show two series
- It can imply spurious correlation by arbitrary scaling (Correct answer)
- It is unsupported by all tools
- It always crashes the browser
Correct answer: It can imply spurious correlation by arbitrary scaling
Independent scaling of two axes can make unrelated series appear correlated, misleading viewers.
Question 5: Which visualization best displays the magnitude of values across two categorical dimensions simultaneously?
- Heatmap (Correct answer)
- Single line chart
- Pie chart
- Histogram
Correct answer: Heatmap
A heatmap uses color intensity in a grid to show values across two categorical axes.
Question 6: To accommodate colorblind viewers, what is the best practice?
- Use only red and green to distinguish series
- Rely solely on color with no other cues
- Use colorblind-safe palettes plus shape or label redundancy (Correct answer)
- Remove all color
Correct answer: Use colorblind-safe palettes plus shape or label redundancy
Combining colorblind-safe palettes with non-color cues like patterns or labels ensures accessibility.
Question 7: What is the purpose of a histogram?
- Show relationships between two variables
- Show the distribution of a single continuous variable via bins (Correct answer)
- Show part-to-whole proportions
- Show geographic data
Correct answer: Show the distribution of a single continuous variable via bins
A histogram groups a continuous variable into bins to reveal the shape of its distribution.
Data Science Data Visualization and Communication 3
Which chart is best for showing a trend in a continuous metric over time?