Build and use issue trees to break any complex problem into a structured set of sub-questions — the foundation of consulting problem-solving.
ISSUE TREE CONSTRUCTION METHOD
Step 1: State the root question precisely ("Why is Company X losing market share?")
Step 2: Identify 2–4 top-level categories (the main branches)
Step 3: For each category, ask "What are the sub-issues within this?"
Step 4: Keep branching until you reach questions answerable with a specific data request
Step 5: Prioritize — which branches are most likely to contain the root cause?Root Question: "Why has an e-commerce startup's repeat purchase rate dropped from 45% to 28%?" Branch 1 — Product Issues → Quality complaints increasing? → Catalog relevance declining for repeat buyers? Branch 2 — Customer Experience → Delivery times increasing? → Return/refund process too difficult? → App performance degrading? Branch 3 — Competitive Issues → Competitor pricing more attractive? → Loyalty program less competitive vs. peers? Branch 4 — Customer Mix Issues → New customers acquired are lower-intent? → Geographic mix shifted to lower-repeat regions? This tree gives you 9 specific investigation questions from one vague problem. That is the power of an issue tree.
Before the GD, build a quick mental issue tree of the topic's sub-issues. When you speak, reference your structure: 'There are three buckets we need to examine here...' This preparation — done in the first 30 seconds of a GD — will make your contributions significantly more structured than others'.
A major private hospital chain's patient satisfaction scores declined 18% year-on-year despite investing in new equipment and facilities. Build a complete issue tree to diagnose the problem.
💡 Hint: Your tree should have at least 3 main branches. Think holistically: before the visit (appointment booking), during (doctor interaction, wait times, nursing care), and after (discharge, follow-up care, billing). Each phase has its own sub-issues.
The 90-Second Issue Tree Verbalization: Choose a problem — 'Why is a Tier 2 city retail mall losing footfall?' Without writing anything, verbally walk through your issue tree in 90 seconds: state the root question, name 3 main branches with brief explanations, state which branch you'd prioritize and why. Record and review for structure and completeness.
Rate yourself honestly on today's performance. Track this across 30 days to measure growth.
McKinsey consultants are trained to never approach a problem as a single question. Every problem is broken into a tree of sub-issues — each branch mutually exclusive, collectively exhaustive (MECE).
A client asks: 'Our profits are declining. What should we do?' A junior consultant starts listing solutions immediately. A senior consultant stops them.
The senior consultant draws an issue tree: Profits = Revenue - Costs. Revenue could be down due to Volume or Price. Volume could be down due to Market Share or Market Size. The team discovers the real issue: market size is shrinking in one segment, but the client has been trying to fix pricing. Wrong solution to wrong problem.
Issue trees prevent you from solving the wrong problem confidently. In a GD, when you structure thinking as a tree, you sound analytical and systematic — exactly what consulting firms look for.
Take any GD topic and draw an issue tree before speaking. Even a simple 2-level tree will make your contribution 3x more structured than average.
Build an issue tree for this problem: 'Zomato's revenue has dropped 20% this quarter.' What are the possible causes? Draw at least 2 levels.
Complete all exercises and the speaking drill before marking complete. This unlocks Day 9.