What are the six M's on a fishbone diagram?

Man (people), machine, method, material, measurement and mother nature (environment). They are the six categories most manufacturing teams use to sort candidate causes; service teams sometimes swap in policies, procedures and place.

Fishbone or 5 Whys first?

Fishbone first. It spreads the possible causes wide, then 5 Whys drills one of them down to a root cause. Doing 5 Whys first tends to chase the first cause somebody names.

How many causes should go on the board?

As many as the team can name in a short, timed session, usually 15 to 30. Then vote or use data to pick the two or three worth testing. A bone with nothing on it is a prompt to think harder, not a finding.

Can the team fill it in remotely?

Yes. Lean Studio is a shared whiteboard, so people add stickies from their own screens and the board updates for everyone.

Who owns the fishbone board?

The person leading the problem, usually the team leader or the Kaizen lead. They keep the head accurate, make sure every chosen cause has a name against it, and bring the board back when a cause is ruled in or out.

Can we use categories other than the six M's?

Yes. Service and office teams often use the four P's: policies, procedures, people and plant. Pick categories that cover the whole process and keep them to six or fewer, or the board turns into a list.

Lean Studio board · Problem solving

Fishbone (Ishikawa) board

In one sentence

A fishbone (Ishikawa) diagram is a cause-and-effect chart that sorts every possible cause of one problem into categories, so a team can see where the causes cluster before it tests any of them.

A fishbone (Ishikawa) diagram sorts the possible causes of one problem into categories, so a team sees where the causes cluster before it goes looking for the root cause. This Lean Studio board has the problem statement at the head and six bones for the six M's: man, machine, method, material, measurement and mother nature.

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When to use it

When to use the Fishbone (Ishikawa) board

At the start of a root cause analysis, once the problem is defined and before 5 Whys narrows one cause.
When a problem has many possible causes and the team keeps arguing about which one matters.
In a kaizen event or an 8D team meeting, to get every idea on the wall in ten minutes.
For recurring defects, downtime or safety events where the first fix did not hold.

What is on the board

1
Problem statement (the head)
One measured problem, for example scrap on Line 2 up from 1.8% to 4.1% since March.
2
Man
Training, staffing, handover, fatigue.
3
Machine
Equipment, tooling, settings, wear.
4
Method
The procedure, the standard, the sequence.
5
Material
Raw material, components, supplier lots, storage.
6
Measurement
Gauges, inspection method, how the data is collected.
7
Mother nature
Temperature, humidity, lighting, layout.

Running it

How to run a Fishbone (Ishikawa) session

1
Write the problem as one measured sentence and put it in the head before anyone names a cause. If the team cannot agree on the sentence, it is not ready for a fishbone.
2
Bring the people who touch the process: an operator from each shift, the setter, maintenance, quality. Five to eight people, typically an hour; a manager in the room should ask questions, not fill bones.
3
Brainstorm in silence for five minutes, one cause per sticky, then place the stickies on the bones. Ask 'why does that happen?' of any sticky that is really a symptom.
4
Read each bone aloud and move the stickies the team disagrees with. Merge duplicates rather than deleting them: two people naming the same cause is information.
5
Pick the two or three causes to test, by data if you have it, by dot vote if you do not, and mark them with a different sticky colour.
6
Give each chosen cause a person and a date to check it on the floor: measure it, watch it, pull the record. The fishbone ends when the causes to test have names against them.
7
Good output: 15 to 30 causes, every bone with something on it, three causes marked, three owners, and a date for the 5 Whys or the test.

Worked example · sample data

Worked example

The sample board has 'Scrap on Line 2 up to 4.1%' at the head. Under Man the team put a new operator on nights and a skipped handover; under Machine, a worn die on press 2 and clamp pressure that drifts; under Method, two versions of the setup sheet in circulation; under Material, coil lot 4471 running thinner than spec; under Measurement, a gauge past its calibration date; under Mother nature, a shop floor at 34°C in July. Read together, three causes could each explain scrap that rose in the same month: the thinner coil lot, the uncalibrated gauge and the two setup sheets. The team marked those three, gave each an owner to check against the scrap records by lot and by shift, and booked a 5 Whys on whichever the data pointed at.

The board shown at the top of this page, read through. Invented data, not a customer.

Common mistakes

A vague head. 'Quality problems on Line 2' produces a fishbone nobody can test; a number and a date do.
Filling the bones from the meeting room. Walk the line first, or bring the people who work it.
Treating the fishbone as the analysis. It lists candidates; the root cause still has to be proven on the floor.
Letting one loud voice decide which cause is right before the board is full.
Leaving a bone empty and moving on. An empty bone usually means nobody in the room knows that part of the process.
Never coming back. Update the board when a tested cause is ruled out, so the team does not test it twice.

How it works in Lean Studio

1
Start from the Fishbone (Ishikawa) template and type the problem into the head.
2
Add a sticky per candidate cause and drop it on its bone; drag it to another bone when the team changes its mind.
3
Mark the causes to test next with a different sticky colour, then take them to a 5 Whys board.
4
Save the finished board to My templates so the next team starts from your version.

Lean Studio boards are drawn with stickies, text, shapes (rectangle, rounded rectangle, ellipse, diamond), arrows and charts, and any board can carry the 15 data widgets, from a scorecard to a kanban. See all widgets and boards.

Also in LeanSuite

Where it goes next in LeanSuite

LeanSuite's RCA Agent drafts 5 Whys, 4M1D and fishbone analyses from a problem and its attached documents.

The causes to test become actions with owners and due dates in a Kaizen project, which has a fishbone section of its own alongside 5 Whys, 5W1H and 4M1D. Kaizen & Projects
If the problem was raised as a tag on the floor, a recurring tag can be escalated into a Kaizen or A3 project in one click, with its history. Daily Issue Management
The RCA Agent drafts a fishbone from the problem description and attached SOPs or manuals, for the team to edit. AI Root Cause Analysis

See AI Root Cause Analysis

Open this board in LeanSuite

Fishbone (Ishikawa) is one of the 30 ready-made boards in Lean Studio, LeanSuite's whiteboard. Try the interactive demo in your browser with sample data, or pilot LeanSuite on your own lines for 90 days, with the setup done by our team.

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In the lean glossary

FAQ

Fishbone (Ishikawa) board

When to use the Fishbone (Ishikawa) board

What is on the board

Problem statement (the head)

Man

Machine

Method

Material

Measurement

Mother nature