Data Analysis and Visualization
What this domain covers
This domain tests whether you can select, build, and read charts, and whether you can perform basic analysis correctly. Know which chart suits which question: bar charts compare categories, line charts show trends over time, scatter plots show relationships between two numeric variables, histograms show the distribution of one numeric variable, pie charts show parts of a whole (and only with few slices), and box plots show spread and outliers.
Concepts to master
Understand chart anatomy: title, axis labels, units, legend, scale, and data source. Know why axis truncation misleads, why 3D and decorative effects distort perception, and why colour should encode meaning rather than decoration. Be familiar with aggregation (sum, count, average), filtering, sorting, grouping, and calculated fields, plus basic trend and comparison analysis. Recognise outliers and decide whether they are errors or genuine extreme values.
Traps in questions
- A pie chart with many small slices or with non-exclusive categories.
- A line chart used for unordered categories, implying a trend that does not exist.
- A histogram confused with a bar chart: histogram bars touch because the x-axis is continuous.
- A truncated y-axis that exaggerates small differences.
- Confusing a stacked chart (totals and composition) with a clustered chart (direct comparison).
Worked rule of thumb
Match chart to question type: comparison → bar; trend over time → line; relationship → scatter; distribution → histogram or box plot; composition → stacked bar or pie with few slices. If a chart's message changes when you start the axis at zero, the chart is not trustworthy.