A fishbone diagram is one of the various techniques available for conducting cause-and-effect analyses. It provides a structured way to identify and organize the potential causes contributing to a particular problem or effect. It allows the establishment and presentation of causal relationships in a straightforward and understandable format.

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Fishbone Diagram
The Role of Fishbone Diagram in Analyzing Cause and Effect

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Definition
A fishbone diagram provides a structured way to identify and organize the
potential causes of a problem (or effect).
Fishbone Diagram 2
It allows to establish and present the
cause-and-effect relationship in an
easy and understandable format.

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Definition
It is called this way because of its visual representation that looks like the
skeleton of a fish.
Fishbone Diagram 3

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Uses
Often used during brainstorming sessions to identify the causes of an
undesirable effect or a problem.
Fishbone Diagram 4
By going through the steps of drawing the
diagram with your team, everyone gains insight
into the cause-and-effect, which makes the
solution easier to find later
One of the various tools that can be used to perform cause-and-effect analysis.

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Uses
Often used in Lean Six Sigma and other quality improvement approaches
to narrow down the area of analysis.
Fishbone Diagram 5
Helps to identify the potential
causes of an effect or problem
in order to identify a solution
that can be effective
Causes
Effects

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Uses
Used to identify the sources of variation within a process which causes a
problem to occur.
Fishbone Diagram 6
This brings attention to the primary factors affecting the quality of a product or service.

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Benefits
Provides clarity regarding the causes of an effect in any problematic scenario.
Fishbone Diagram 7
The outcome of the fishbone analysis will provide useful information to later problem-
solving tools.

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Benefits
Fishbone Diagram 8
Identifies the potential factors that
may cause an effect to prevent future
problems (cause prevention).
Can be used to identify the causes of
risks.
A teamwork exercise that helps to
capture and organize people's
knowledge of a process.
Can be used in product and process
design to plan new processes.

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Structure
The first step in conducting a fishbone analysis is to clearly define the
effect.
Fishbone Diagram 9
This could be a quality issue, a
technical issue, or simply not
meeting a performance target.

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Structure
The effect will become the head of the fishbone.
Fishbone Diagram 10
Effect
• Should be brief.
• Use numbers where possible.
Take a moment with the team to think about the effect. Does everyone agree on what it is?

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Structure
The causes will be placed in the branches of the chart.
Fishbone Diagram 11
Each cause needs to be put into a
category for easier sharing and
reference
Effect
Cause
Category

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Structure
A fishbone diagram allows to identify the hierarchy of causes including the
possible root causes.
Fishbone Diagram 12
Lines can be used to connect the series of linked causes
Root causes are normally
those at the ends of the
chains of causes that do not
have any sub causes
Effect
Potential
cause
Sub cause
Cause
Category

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Structure
Combining the fishbone with the 5 whys gives the analysis an extra
dimension.
Fishbone Diagram 13
1
2 3
Effect
Category
Potential cause
5 whys can be used to dig deeper and go beyond symptoms

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Grouping Potential Causes
Potential causes in a fishbone diagram are normally grouped into
categories for easier sharing and reference.
Fishbone Diagram 14
These categories are used to label the different branches on the fishbone diagram.

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Grouping Potential Causes
There are different approaches of constructing a fishbone diagram
indicated by the branch labels.
Fishbone Diagram 15
4
6
8
There is no right or wrong way to do that!

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Grouping Potential Causes – 4 Ms
One of the most basic forms to group the potential causes of a problem or
effect.
These categories typically include Man, Method, Machine and Material.
Fishbone Diagram 16
Material
Method
Machine
Man
4

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Grouping Potential Causes – 6 Ms
The most common way to categorize potential causes of a problem or
effect.
Commonly used in manufacturing and production environments.
Fishbone Diagram 17
Measurement
Environment
Method
Machine
Material
Man
6

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Grouping Potential Causes – 6 Ms
Man – Anyone involved with the process and contributes to the effect
Including governance and support functions.
Fishbone Diagram 18

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Grouping Potential Causes – 6 Ms
Method – How the process is performed and the specific requirements for
doing it.
Fishbone Diagram 19
Procedures
Common
practices
Work
instructions
Rules and
policies

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Grouping Potential Causes – 6 Ms
Machine – The machinery, equipment and tools required to perform the
process.
Fishbone Diagram 20

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Grouping Potential Causes – 6 Ms
Material – All the materials needed to perform a process.
Fishbone Diagram 21
Parts Information
Packaging
Raw
materials
Paperwork

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Grouping Potential Causes – 6 Ms
Environment – The conditions in which the process operates.
Fishbone Diagram 22
Time Culture
Temperature
Location

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Grouping Potential Causes – 6 Ms
Measurement – The data and metrics that are used to evaluate the
performance of the process.
Fishbone Diagram 23

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Grouping Potential Causes – 6 Ms
Different names may be used for the same category depending on the
situation and on the user's choice.
Fishbone Diagram 24
Man – Men – Manpower – People – Labor
Machine – Machinery – Equipment – Tools – Systems
Measurement – Metrics – Inspection
Method – Process – Procedure
Environment – Mother Nature – Milieu

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Grouping Potential Causes – 8 Ms
Adds Management and Maintenance to the 6 M categories.
Fishbone Diagram 25
8
Man Method
Material Machine
Mother nature Measurement
Management Maintenance
4 Ms
4 Ms
4 Ms

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Grouping Potential Causes
When you are working on an affinity diagram, you can use the titles of the
affinity groups as the basis for categorization.
Fishbone Diagram 26
Social
Economic Cultural
The items within each
affinity group can be
the potential causes
Cultural
Economic
Social

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Grouping Potential Causes
When the effect results from a documented or mapped process, the
process steps can be used as the basis for categorization.
Fishbone Diagram 27
10
Prepare
expense report
Employee
20
Approve
and Sign
Dept. Manager
30
Approve
and Sign
Controller
40
Pay
employee
Payroll Officer
The process input
variables (design factors)
can be the potential causes
Pay employee
Approve and sign
Prepare expense report

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Grouping Potential Causes
You may also create subcategories of a main category and include it in new
branches.
Fishbone Diagram 28
Material
Measurement
Man
Suggestions
Man
Kaizens
Method
Man
Training
Remember to avoid writing real names of persons under the “Man” category.

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Grouping Potential Causes
You may even rename or create your own branches that best suit your
project.
Fishbone Diagram 29
Heart
Mind
Soul
Body
Fishbone analysis can also be used in our personal lives to create ideas about the
certain personal issues and how to avoid them.

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Grouping Potential Causes
Typical Categories for Manufacturing and Non-Manufacturing Processes.
Fishbone Diagram 30
Machine
Manpower
Material Measurement Method
Environment
Manufacturing
Equipment
People
Policies and Procedures
Environment
Administration
and Services

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Steps for Drawing a Fishbone Diagram
Fishbone Diagram 31
With your team, clearly define the effect that you want to work on
• Write the effect statement in a box at the center right of a large piece of paper (or
on a wall).
• Draw a long horizontal line pointing to the box.

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Steps for Drawing a Fishbone Diagram
Fishbone Diagram 32
Identify the cause categories using the 4Ms or any other approach
• Write them in boxes parallel to the horizontal line.

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Steps for Drawing a Fishbone Diagram
Fishbone Diagram 33
Use brainstorming to log all possible causes under the appropriate categories
• Start with the main causes and then the secondary causes and so on.
• Use 5 whys to get to the root causes.

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Steps for Drawing a Fishbone Diagram
Fishbone Diagram 34
Take time to ensure the appropriateness of the recorded information
• Update the chart as new potential causes become apparent.

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Steps for Drawing a Fishbone Diagram
Fishbone Diagram 35
Highlight or assign numbers near to the key causes to indicate their relative importance
• Draw links between causes that are related.
2
1
3
4
5

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Steps for Drawing a Fishbone Diagram
Fishbone Diagram 36
If necessary, collect data to confirm key causes are real
• Plan and implement actions to address the key causes.

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Example – Increased Invoice Errors
Fishbone Diagram 37
Increased
Invoice Errors
Cumbersome process
Manual data entry
Inadequate printers
Incompatible system
System not integrated
Noisy office
Poor ergonomics
Poor technical support
Low morale
Poor audit system
Delayed paper supply
Increased workload
Man
Measure
Material
Environment Equipment Method
Poor paper quality

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Example – Increased Coolant Consumption
Fishbone Diagram 38
High Coolant
Consumption
Man
Measure
Material
Environment Machine Method
Adjusting concentration settings
Blocked hoses
Machine leakage
Materials in trench
Machine breakdown Adding WBLF to the tank
Evaporation in summer
Poor shift communication
Delayed measurement
WBLF measured for all lines
Biocide level
Antifoam level
Lack of training
Absenteeism
Rounding

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Example – Coffee Flavor
Fishbone Diagram 39
Over roasting
Not fresh coffee beans
Unclean coffee maker
Low water quality
Cleaning SOP
not followed
Machine
Coffee not tasting
good
Material
Using water from
the tap
Beans roasted
some time ago
Long roasting
period
Current
settings

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Further Information
Be aware of adding causes which are actually solutions.
Fishbone Diagram 40
The main idea behind the fishbone
analysis is to brainstorm all possible
causes that may contribute to a
problem, and not brainstorm solutions

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Further Information
A cause-and-effect matrix can be used to prioritize the causes of the
problem.
Fishbone Diagram 41
Prioritizing and selecting the key causes
will minimizes the need for more
statistical analysis of inputs that are
unlikely to have an impact on the
output

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Further Information
Another way of highlighting the structure of the possible causes is to use
the tree diagram.
Fishbone Diagram 42

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Further Information
The measure of success for a fishbone diagram is typically the quantity of
ideas generated rather than their quality.
Fishbone Diagram 43
The goal is to gather a wide range of possible causes, which can then be evaluated and
refined as needed.

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Further Information
A fishbone diagram can also be used to structure the thoughts of a team.
Fishbone Diagram 44
Sometimes it is useful to change the effect statement into the ideal situation and ask
the team to brainstorm what produces this ideal situation.

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Further Information
Sometimes it is useful to brainstorm out the ideas first then organize them
by category later.
Fishbone Diagram 45
People sometimes tend to focus more on the categories than the content and this
slow down and restricts their thinking.

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