Root Cause Analysis
• Analyze
• Kaizen Facilitation
Objectives
• Learn and be able to apply a fishbone diagram
• Utilize “Why” analysis technique to uncover causes
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“Why” Analysis
• Question asking technique used to explore the cause and
effect relationships underlying a particular problem
• Four to five iterations of asking why is generally sufficient
to get to a root cause, but may go more
• EXAMPLE: The vehicle will not start (problem statement)
• Why? – The battery is dead
• Why? – The alternator is not working
• Why? – The alternator belt is broken
• Why? – The belt was beyond its useful life
• Why? – The vehicle was not maintained per the recommended schedule
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Tips For Successfully Using “Why” Analysis
• Root cause of the vehicle example appears to be
the lack of scheduled maintenance… this is a
process that can be improved
• You know when you have gotten to the cause
when the answer points to a process that is not
working or does not exist
• The root cause generally is not time, money, or
manpower
• Processes fail, not people or money, so ask the
question “Why did the process fail?”
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What is a Fishbone Diagram?
• The Fishbone diagram (or Ishikawa Diagram) is used to identify
possible causes for an effect
• Causes are grouped into major categories to identify the sources of
variation through the 6M’s
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Manpower
Machines
Materials
Methods
Measurements
Mother nature [environment]
Fishbone Diagram - Example
Materials
Stuck
Cones
Damaged
containers
Methods
Yard
Planning
Unrealistic
Deadlines
Incorrect
Stow Plans
Manpower
New Driver
Untrained
Driver
Driver in Bad
Mood
POOR CRANE
PRODUCTION
CAUSES
Condition
of Crane
Broke cell
guides
Type of
Crane
Machines
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EFFECT
Additional
long travels
Physical
Terminal
Layout
High winds
Mother Nature
Service
Overdue
Operating
with Defect
Measurements
Why Use a Fishbone?
• Groups potential causes for defects into logical categories
• Helps teams work together to get to root cause
• Highlights where additional data gathering needs to occur
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Step 1: Determine the Problem/Issue
• To construct a fishbone:
• Start with stating the problem in the form of a question, such as “Why is
crane production low?”
• Agree on the problem (effect) and place it in a box at the “head” of the
fishbone
Why is Crane
production low?
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Step 2: Establish the Categories
• Determine which categories you will use to find causes and draw the
lines (bones)
• Feel free to modify the categories for your project and subject matter
• Most common categories called 6 M’s:
• Manpower
• Machines
• Materials
• Methods
• Measurements
• Mother nature
[environment]
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Machines
• The Machines category groups root causes related to tools or
equipment
• Examples of questions to be asked:
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Was the correct tool/tooling used?
Does it meet production requirements
Is the machine properly maintained?
Was the equipment used within its capabilities and limitations?
Are all controls clearly labeled
and/or color-coded or differentiated?
Machines
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Y
Methods
• The Method category groups root causes related to how the work
is done
• Examples of questions to be asked:
• Are the work instructions clearly written & complete?
• Are mistake-proofing devices/techniques employed?
• How many “if necessary” and “approximately” phrases are found in this
process?
Y
• Are features of the process critical to
safety clearly spelled out?
Methods
• Is the work standard upgraded and
to the current revision?
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Materials
• The Materials category groups root causes related to parts, supplies,
forms or information needed to execute the process
• Examples of questions to be asked:
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Is all needed information available and accurate?
Was the material substituted?
Was the material defective?
Was the raw material the wrong
type for the job?
• Was the material handled properly
(stored, dispensed, used & disposed)?
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Materials
Y
Measurements
• The Measurement category groups root causes related to the
measurement and measuring of a process activity or output
• Examples of questions to be asked:
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Is there a metric issue?
Is there a valid measurement system?
Is the data good enough?
Is data readily available?
Does the measuring gage have
proper measurement resolution?
Measurements
Y
Manpower
• The Manpower category groups root causes related to people,
staffing and organizational structure
• Examples of questions to be asked:
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Was the proper training to perform the task administered to the person?
Was too much judgment required to perform the task?
Were guidelines for judgment available?
Is fatigue a contributing factor?
Manpower
How much experience does the
individual have in performing this task?
Y
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Mother Nature (Environment)
• The Mother Nature category groups root causes related to the work
environment, market conditions, and regulatory issues
• Examples of questions to be asked:
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Is the workplace safe and suitable/ comfortable?
Are outside regulations impacting the business?
Is the process affected by temperature changes over the course of a day?
Are associates distracted by noise,
Y
uncomfortable temperatures,
fluorescent lighting, etc.?
Mother Nature
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Step 3: Brainstorm Causes
• For each category, brainstorm possible root causes of the problem
that may be related to the problem/ issue
• For each cause identified, continue to ask “why does that happen?”
and attach that information as another line (bone) of the category
branch
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Step 4: Review the Diagram
• The diagram should now
show all of the possible
causes of the problem
that you can think of
• Prioritize the key causes
identified on the
fishbone
• Agree on which of these
possible causes are
actually contributing
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Summary
1. Identify the problem or issue
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Draw horizontal line across center of page
Write problem at fish head
2. Establish the categories
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Use the 6M’s: Manpower, Machine, Method, Measurement,
Material, Mother Nature (Environment) - or choose your own
Draw lines (bones) and the labels
3. Brainstorm/ record ideas onto fishbone
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Create sub-branches as needed
4. Review completed diagram and set focus
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Score / Vote or Rank as appropriate to group thoughts, or prioritize
the issues by data analysis (most frequently occurring) or cost
impact on the process or risk of failure/ work stoppage, etc.
Exercise: Create a Fishbone Diagram
• With your team, construct a detailed Cause and Effect Diagram on
the process / example presented
• Identify and label categories
• Examine using the “why” analysis
• Brainstorm as many inputs as possible with each branch and/ or sub-branch
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Review
• Learn and be able to capture thoughts using a
fishbone diagram
• Learn to apply “Why” analysis technique to
uncover root causes
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Why Analysis Example
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Why Analysis Example
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Why Analysis Example
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Why Analysis Example
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Why Analysis Example
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Why Analysis Example
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Fishbone Example
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Fishbone
Example
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