Two classic root cause analysis techniques with different approaches. Learn when to drill deep vs. when to go wide.
An iterative questioning technique that drills down to root causes by asking 'Why?' repeatedly (typically 5 times).
A visual brainstorming tool (also called Ishikawa or cause-and-effect diagram) that maps all potential causes across categories.
| Aspect | Five Whys | Fishbone Diagram |
|---|---|---|
| Approach | Linear, drilling down a single causal chain | Branching, exploring multiple cause categories simultaneously |
| Structure | Sequential questions in a chain | Visual diagram with main categories and sub-causes |
| Scope | Deep but narrow - follows one path to root cause | Wide but shallow - maps many potential causes |
| Best Problem Type | Problems with a single primary root cause | Complex problems with multiple contributing factors |
| Time Required | Quick - often 10-20 minutes | Longer - typically 30-60 minutes with a team |
| Team Size | Works well solo or with 2-3 people | Best with 4-8 people for diverse perspectives |
Yes, they're complementary. Use a Fishbone Diagram first to identify all potential cause categories, then use Five Whys to drill deep into the most likely causes identified.
Five is a guideline, not a rule. Simple problems might need only 2-3 whys; complex ones might need more. Stop when you reach a cause you can take action on.
Common categories include the 6 M's: Man (people), Machine (equipment), Method (process), Material, Measurement, and Mother Nature (environment). Adapt these to your context.
Both help prevent recurrence, but Fishbone is better for systemic issues since it maps the full cause landscape. Five Whys is better for addressing a specific causal chain quickly.
Both tools are free to use with no signup required. Your data stays in your browser.