Data Interpretation and Analytical Reasoning
Data Interpretation and Analytical Reasoning
This domain tests the ability to read tables, charts and short data sets and to make comparisons, calculate rates and draw only supported conclusions. Questions often combine percentages, ratios and trends, so the main skill is choosing the right base and operation.
Core rules
- Read the title, units, legend and time period before calculating.
- Percentage change = change ÷ original × 100; the original is the earlier or base value, not the later one.
- Percentage points describe a difference between two percentages; percent describes a relative change.
- For share, divide the part by the correct total for that year or category.
- Check whether data are cumulative or period figures; do not add cumulative totals.
- When comparing categories, hold the denominator constant or state the base.
Worked example
Revenue was 400 million in 2022, 500 million in 2023 and 600 million in 2024. The 2023-2024 increase is 100 million. Percentage increase = 100 ÷ 500 × 100 = 20%, not 100 ÷ 400 = 25%. The 25% figure would compare 2024 with 2022, not with the previous year. If a question asks for the share of 2024 revenue in the three-year total, the denominator is 400 + 500 + 600 = 1,500 million, giving 40%.
Traps
- Using the wrong base year.
- Confusing percentage with percentage point.
- Reading a graph's height without checking the axis start.
- Mixing units such as millions and billions.
- Selecting a trend from too few points.