Master Problem Solving with WHAT, WHY, HOW, and WHAT‑IF Trees

The author recently read Sun Shuxia’s new book Structured Analysis , which presents a rich, systematic set of problem‑analysis methods. One chapter describes three logical trees—WHAT, WHY, and HOW—that help meticulously organize problem‑solving logic.

Building on these three trees, the article adds a fourth tree, the WHAT IF tree, and shares personal refinements and drawing techniques to enrich their expressive power.

WHAT Tree: Classification and Layering

The WHAT tree is the starting point of logical analysis. Its core task is to clearly, finely, and structurally separate the problem or object, focusing solely on “what it is” without addressing causes or solutions.

A good WHAT tree has two features:

Classification – horizontal expansion. For example, “poor company performance” can be divided into “revenue issues”, “cost issues”, “team issues”, and “product issues”.

Layering – vertical deepening. Each category can be further broken down, such as “revenue issues” into “customer count”, “average order value”, and “repurchase rate”.

<code>Company performance poor
├── Revenue issues
│   ├── Declining customer count
│   ├── Lower average order value
│   └── Falling repurchase rate
├── Cost issues
│   ├── High fixed costs
│   └── Rising material prices
└── Team issues
    ├── Severe staff turnover
    └── Ineffective performance system
</code>

The tree should be expanded to a reasonable depth, adhering to the MECE principle (Mutually Exclusive, Collectively Exhaustive).

WHY Tree: Finding Causes

After the WHAT tree defines the problem, the WHY tree asks “Why is this happening? What is the root cause?” It is a cause‑and‑effect tree whose trunk is the problem, branches are causes, and roots are fundamental reasons.

<code>Revenue decline
├── Customer count drop
│   ├── Insufficient market promotion
│   └── Competitors attracting customers
├── Average order value drop
│   ├── Aggressive discounting
│   └── Loss of premium customers
└── Repurchase rate fall
    ├── Decreased product satisfaction
    └── Poor customer service experience
</code>

The analysis often combines with the “5 Whys” method, distinguishing surface causes from root causes and avoiding circular reasoning.

HOW Tree: Designing Countermeasures

When the WHAT tree clarifies the issue and the WHY tree uncovers causes, the HOW tree answers “What should we do? How should we respond?” It is a countermeasure tree whose trunk is the goal, branches are strategic directions, and leaves are concrete actions.

<code>Increase revenue
├── Grow customer base
│   ├── Increase advertising spend
│   └── Launch viral referral campaigns
├── Raise average order value
│   ├── Introduce premium products
│   └── Design bundle pricing
└── Boost repurchase rate
    ├── Implement loyalty points system
    └── Improve after‑sale service quality
</code>

The HOW tree emphasizes “targeted solutions” and the need to compare, prioritize, and evaluate measures to ensure implementation.

WHAT IF Tree: Predictive Evaluation

The WHAT IF tree extends logical analysis to scenarios, asking “What happens if we do this? What if we don’t?” Its trunk is a strategy, branches are possible situations, and leaves are projected outcomes.

<code>Launch new product
├── Positive market response
│   ├── Sales increase
│   └── Brand popularity rise
├── Neutral market response
│   ├── Break‑even
│   └── Opportunity for further optimization
└── Negative market response
    ├── Inventory buildup
    └── Brand damage
</code>

This tree helps anticipate risks, forecast effects, and adjust strategies, reflecting systematic thinking and risk awareness.

Four Trees and the DEED Framework

The author links the three original trees to the first three problem types in the DEED model (Describe & Understand, Explain & Trace, Evaluate & Decide) and maps the WHAT IF tree to the fourth type (Estimate & Predict), creating a cohesive four‑tree approach.

Refined Drawing Guidelines

WHAT tree: solid lines without arrows to show composition.

WHY tree: arrows pointing upward from causes to effect.

HOW tree: arrows pointing downward from goal to actions.

WHAT IF tree: dashed lines with arrows, optionally annotated with probability or risk level.

These visual cues make each tree’s purpose clearer.

Integrating the four trees into a quadrant or flow diagram illustrates their sequential relationship: start with WHAT, analyze with WHY, devise with HOW, and validate with WHAT IF, providing a robust tool for complex problem handling.

Each tree cultivates a specific skill: the WHAT tree builds structural thinking, the WHY tree sharpens insight, the HOW tree enhances actionable capability, and the WHAT IF tree expands imagination.

Together they form a “logical forest” that supports daily work, analysis, communication, and decision‑making.