Data Interpretation Tips - Quick Revision
Data Interpretation Tips - Quick Revision
Key Points (One-Liners)
- Always read the title, units and footnotes first – 30 % errors vanish here.
- Round numbers to nearest 5 or 10 to cut calculation time by 50 %.
- In pie-charts, 1 % = 3.6°; multiply % value by 3.6 to get central angle.
- Bar/line with “years” → look for constant difference or CAGR, not absolute jump.
- Table with missing value → use vertical & horizontal totals to cross-check.
- Ratio questions: cancel common zeros first, then divide.
- Average growth rate ≈ (Last – First) ÷ (No. of years – 1) for linear data.
- Two-chart combo → link common parameter (e.g., sales in bar & profit in line).
- “Maximum % increase” needs denominator of previous year, not absolute value.
- In stacked bar, individual value = total – sum of rest.
- Approximation trap: if options are > 15 % apart, round aggressively.
- Never mix units – convert ‘000 or lakh to base unit before calculating.
- DI sets are 1-mark each; spend ≤ 2 min per question, flag and move on.
- Last digit check (unit place) often eliminates 3 options in multiplication.
- Always re-check the row/column you picked; 10 % mistakes are copy-errors.
| Formula/Rule |
Application |
| % change = (New – Old) ÷ Old × 100 |
Any increase/decrease question |
| 1 % of pie = 3.6° |
Convert % share to angle |
| Avg. = Total ÷ Number |
Mean, per-capita, per-day sums |
| CAGR = (Ending ÷ Beginning)^(1/n) – 1 |
Compounded yearly growth |
| Ratio A:B = A÷GCD : B÷GCD |
Simplify before comparing |
| Market share = (Firm sales ÷ Total sales) × 100 |
Quick dominance check |
| Difference % = |
A–B |
| Total of stacked bar = Σ individual |
Verify missing segment |
| Angle to % = Angle ÷ 3.6 |
Reverse of pie-chart trick |
| Effective % (successive) = a + b + ab⁄100 |
Two-year hikes, discounts |
Memory Tricks
- “3-6 Pie” – 1 % = 3.6° (think 36″ in a yard).
- “Round-Row-Read” – Read headings, Round numbers, Row-check totals.
- “Denominator Decides” – % change always sits on the old value.
- “Last Digit Lock” – multiply only unit digits to pick right option fast.
- “BAR=Before-After-Reason” – compare two bars: spot reason in axis label.
Common Mistakes
| Mistake |
Correct Approach |
| Using wrong year’s value as base for % change |
Always use immediate previous year |
| Treating stacked height as single value |
Subtract others to isolate layer |
| Ignoring units (‘000, lakh, crore) |
Write unit conversion on sheet first |
| Calculating CAGR with simple average |
Use (Ending/Beginning)^(1/n)–1 |
| Rounding before final step |
Round only after last operation |
Last Minute Tips
- Carry a translucent scale – align for exact bar/table line.
- Do easy single-chart sets first; accumulate marks quickly.
- Write % fractions (½, ⅓, ¼) beside pie slices – speeds comparison.
- If options far apart, estimate; if close, calculate exact.
- Mark data you already used; prevents re-reading same numbers.
Quick Practice (5 MCQs)
Q1. If exports in 2022 = 240 cr and 2021 = 200 cr, % increase is?
≈ (240–200)/200 × 100 = 20 %
Q2. Pie angle for 25 % share is?
25 × 3.6 = 90°
Q3. Average of 45, 55, 50, 60?
(45+55+50+60)/4 = 52.5
Q4. A stacked bar total 380; three parts 120, 90, 100. Missing part?
380 – (120+90+100) = 70
Q5. Sales rose 10 % then 20 %. Net effective rise?
10+20+(10×20)/100 = 32 %
BETA
