Question 33
Domain 2: Data ProcessingWhich chart is usually best for inspecting counts of a single categorical feature such as `device_type`?
Correct answer: A
Explanation
A bar chart is used to display counts for categories in a single categorical feature, such as "device_type." It shows each category as a separate bar, making it easy to compare frequencies across groups.
Why each option is right or wrong
A. Bar chart
For a single categorical variable like `device_type`, the standard display is a bar chart because it compares discrete category frequencies with separate bars on a common baseline. By contrast, histograms are for continuous numeric data, and pie charts are less effective for precise count comparison across multiple categories.
B. Scatter plot
Scatter plots show relationships between two numeric variables, not category counts.
C. Residual plot
Residual plots diagnose model errors after fitting, not raw categorical frequency distributions.
D. ROC curve
ROC curves evaluate binary classifier performance across thresholds, not feature-level counts.