Data Interpretation and Analytical Skills
What this domain tests
Data interpretation gives you tables, charts, or short datasets and asks for comparisons, rates, and valid conclusions. It tests careful reading and proportional reasoning more than complex calculation.
Core rules and concepts
- Read the title, units, footnotes, and base period before calculating.
- Percentage of total and percentage change are different. A department can have the largest share and still have the smallest growth.
- Index numbers compare to a base year, which equals 100.
- Rates such as per capita or per 1,000 people allow fair comparison between populations of different sizes.
- Weighted averages: average percentages only after weighting by each group's size.
- Correlation is not causation. Look for confounders and for whether the data is observational.
- Do not extrapolate beyond the data. Not stated is a valid answer.
Worked example
Department A had a budget of 200 and spent 180. Department B had a budget of 500 and spent 450. Which underspent by the larger percentage?
A underspent 20, which is 10% of 200. B underspent 50, which is 10% of 500. The percentages are equal, although B's absolute underspend is larger. If the question asked for the larger amount, B would win.
Traps that cost marks
- Reading the wrong axis or the wrong year.
- Mixing thousands and millions.
- Averaging percentages without weighting.
- Assuming a rising trend will continue.
- Choosing a conclusion that is true in the table but does not answer the question.
- Ignoring small sample sizes.