Data interpretation questions test your ability to extract insights from exhibits—charts, tables, and graphs. They're especially common at McKinsey (with their chart-heavy cases) and in written case tests.
Why Data Interpretation Is Tested
Consultants spend significant time analyzing data and communicating findings. Interviewers want to see that you can:
- Quickly scan an exhibit and identify what matters
- Perform the right calculations
- Connect numbers to business insights
- Communicate findings clearly
The SCAN-STRUCTURE-CALCULATE-SYNTHESIZE Method
Step 1: SCAN (10 seconds)
- What type of chart is it? (bar, line, pie, table)
- What are the axes/headers?
- What time period?
- What units?
Step 2: STRUCTURE (10 seconds)
- What question am I trying to answer?
- What data points do I need?
- What calculation makes sense?
Step 3: CALCULATE (30-60 seconds)
- Extract the numbers
- Perform the math
- Round appropriately
Step 4: SYNTHESIZE (15 seconds)
- What does this mean for the business?
- Is this good or bad?
- What's the "so what"?
Common Chart Types
Bar Charts
Look for: Comparisons between categories, trends over time
Common calcs: Differences, ratios, growth rates
Line Charts
Look for: Trends, inflection points, seasonality
Common calcs: Growth rates, slopes, projections
Stacked Bar/Area
Look for: Composition changes, relative share
Common calcs: Mix shift, percentage of total
Waterfall Charts
Look for: Bridge from start to end, positive/negative contributors
Common calcs: Net change, largest drivers
Pie Charts
Look for: Relative proportions, dominant segments
Common calcs: Percentage shares, concentration
Typical Math Operations
| Question Type | Calculation |
|---|---|
| "How much did X grow?" | (New - Old) / Old × 100% |
| "What's the difference?" | Absolute: A - B; Relative: (A-B)/B |
| "What's the average?" | Sum / Count |
| "What's X as % of total?" | X / Total × 100% |
| "How does X compare to Y?" | Ratio: X/Y or Difference: X-Y |
3 Worked Chart Examples
Example 1: Revenue Bar Chart
Chart shows: 2022 revenue $80M, 2023 revenue $92M
Question: What was the growth rate?
Calc: ($92M - $80M) / $80M = 15%
Insight: "Revenue grew 15% year-over-year, which is above the industry average of 8%."
Example 2: Cost Breakdown Pie
Chart shows: Labor 45%, Materials 30%, Overhead 15%, Other 10%
Question: If we reduce labor costs by 10%, what's the total cost impact?
Calc: 45% × 10% = 4.5% total cost reduction
Insight: "A 10% labor efficiency improvement would reduce total costs by 4.5%."
Example 3: Market Share Stacked Bar
2022: Company A 40%, B 35%, Others 25%
2023: Company A 35%, B 40%, Others 25%
Question: What happened to competitive dynamics?
Insight: "Company B overtook Company A, gaining 5 share points. Others remained stable, so B's gain came directly from A's loss."
Common Mistakes
- Zooming into noise — Small variations might not be meaningful
- Forgetting to normalize — Compare percentages, not absolutes when bases differ
- Ignoring units — Millions vs thousands vs percentage points
- Missing the big picture — Don't just report numbers; explain significance
- Not sanity checking — Does your answer make logical sense?
Where to Practice
Data interpretation combines reading skills with math. Build both:
- Case Math Drills — Business calculation practice
- Mental Math Sprint — Speed with numbers
- Brain Teasers — Logical analysis
Charts tell stories. Your job is to read them correctly and communicate the narrative.