Data Interpretation from Tables and Charts
What you must understand
You will be shown a table or chart with several rows, columns, or categories, and asked to compute totals, differences, averages, ratios, or percentage shares. The skills are reading accurately, locating the right cell, and performing the required operation without being distracted by irrelevant figures.
Method
First read the title, units, and any footnotes. Check whether figures are in thousands or millions and whether the chart axis starts at zero. Identify exactly which row and column the question names, then extract only those values. For percentage-share questions, the denominator is the total of the relevant group, not the grand total, unless stated.
Traps
- Axis scales that do not start at zero, exaggerating differences.
- Units in thousands while the question asks for an absolute figure.
- 'Total' rows or columns included accidentally in an average.
- Asking for a share of a subgroup when the candidate divides by the grand total.
- Percentages that do not sum to 100 because of rounding; do not force them.
Worked example
A table shows sales of 40, 60, 80 and 20 units across four quarters. Total = 200. The share of Quarter 3 is 80 ÷ 200 = 40%. If asked for the average per quarter, divide by 4: 200 ÷ 4 = 50 units. The trap is dividing 80 by 4 instead of by the total when a share is requested.