DAC Data Visualization & Reporting 3 — Questions and Answers
Question 1: When should you use a line chart instead of a bar chart?
- To compare discrete categories
- To show trends over continuous time (Correct answer)
- To display parts of a whole
- To rank items alphabetically
Correct answer: To show trends over continuous time
Line charts are ideal for showing how a value changes over continuous time.
Question 2: What is 'data-ink ratio' as described by Edward Tufte?
- The ratio of printer ink to paper cost
- The proportion of ink used to display actual data versus decoration (Correct answer)
- The number of colors per chart
- The pixel density of a screen
Correct answer: The proportion of ink used to display actual data versus decoration
Data-ink ratio measures how much of a chart's ink represents real data versus non-essential decoration.
Question 3: A stakeholder wants to compare the composition of total sales across five regions over four quarters. Which chart works best?
- Single pie chart
- Stacked bar chart by quarter (Correct answer)
- Scatter plot
- Gauge chart
Correct answer: Stacked bar chart by quarter
A stacked bar chart by quarter shows both totals and regional composition over time.
Question 4: What is the main purpose of adding filters to an interactive report?
- To increase file size
- To let users focus on specific subsets of data (Correct answer)
- To hide the data source
- To slow down queries
Correct answer: To let users focus on specific subsets of data
Filters allow users to narrow the view to relevant subsets of the data.
Question 5: Which practice improves the storytelling quality of a report?
- Presenting charts without any titles or labels
- Guiding the reader with annotations and a logical flow (Correct answer)
- Using random chart orderings
- Removing all context and comparisons
Correct answer: Guiding the reader with annotations and a logical flow
Annotations and a logical narrative flow help readers interpret and act on the data.
Question 6: A dual-axis chart is most useful when you need to:
- Show two measures with different scales together (Correct answer)
- Display a single metric
- Replace a data table
- Show geographic distribution
Correct answer: Show two measures with different scales together
Dual-axis charts let you plot two measures with different scales on the same chart for comparison.
Question 7: What does 'small multiples' refer to in data visualization?
- Using tiny fonts
- A series of similar charts using the same scale for easy comparison (Correct answer)
- Rounding numbers down
- A single very small chart
Correct answer: A series of similar charts using the same scale for easy comparison
Small multiples are a grid of similar charts with shared scales, enabling quick comparison across categories.
DAC Data Visualization & Reporting 3
When should you use a line chart instead of a bar chart?