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description: Use when decomposing a complex problem into mutually exclusive, collectively exhaustive parts
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# Issue Tree (McKinsey)

Break down a complex problem into a MECE (Mutually Exclusive, Collectively Exhaustive) tree structure so every sub-problem is distinct and no part of the problem is missed.

## Steps

1. **Define the core question** — Frame the problem as a single, clear question at the top of the tree.
2. **Create the first split** — Divide into 2-4 branches that are mutually exclusive (no overlap) and collectively exhaustive (no gaps).
3. **Decompose each branch** — Break each branch into further sub-questions, maintaining MECE at every level.
4. **Go 2-3 levels deep** — Continue until each leaf node is specific enough to be analyzed or answered directly.
5. **Prioritize branches** — Assess which branches have the highest impact or are most uncertain, and focus effort there.

## Output Format

A hierarchical tree diagram (or indented outline) with the core question at the root, 2-3 levels of MECE branches, and priority markers on the most important branches.