Root Cause Analysis - Overview
Root Cause Analysis
and
Corrective Action (RCCA)
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RCCA - Learning Objectives
The purpose of this module is to:
• Apply the “5-why” technique in problem
solving analysis.
• Identify and understand the direct,
contributing and root cause of a problem.
• Learn the 2 types of corrective action.
• Utilize a Corrective Action Matrix form to
track and drive action item completions.
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Root Cause Analysis - An Overview
Root Cause Analysis and Corrective
Action (RCCA) is a process for :
• Finding the true cause(s) of an event
• Identifying and implementing corrective
actions
• Assessing the effectiveness of corrective
actions
• Preventing recurrence of the events
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Why Root Cause Analysis ?
Integral part of Continuous Improvement
If we do not take action on problems,
we will be wasting our time and all involved
will lose interest.
• Our Customers expect it !
• ISO 9001-2000 requirement
• Makes good Business sense
• Keeps us from passing on problems to
internal and external CUSTOMERS
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DMAIC process applied to RCCA
Quantify
Problem
Control –
Form Team
Scope project
Standardize
Improvement
RCCA
Make
Improvement
Measure
Analyze
Investigate
Root
Cause
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(Customer complaints,
Audit findings,
Production, Inspection Data,
Product returns, Warranty etc)
Understand and State the Problem
•
Understand the Problem
• From the event, what is the problem to
be solved,
or
what is the customer’s concern?
•
More than one Problem?
• An event could have more than one problem,
with a root cause for each problem.
If you cannot say it simply, you do not
understand the problem!
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A Cause . . .
Is a set of circumstances or conditions that:
• Allows a condition to exist or an event
to happen,
Or
• Makes a condition exist or an event happen
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The Critical Five
Direct Cause: The cause that directly resulted in
the event.
(The first cause in the chain.)
Contributing Cause: The cause(s) that contributed to an
event but, by itself, would not have caused the event.
(The cause after the direct cause.)
Root Cause: The fundamental reason for an event,
which if corrected, would prevent recurrence.
(Last cause in the chain.)
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The Critical Five
Specific Corrective Action: Action(s) taken to correct or
improve conditions noted in the event, by changing the
direct cause
or,
The direct cause and the effect.
Preventative Corrective Action: Action(s) taken that
prevent recurrence of the condition noted in the event.
(Preventive actions must directly address the root and
contributing causes to be effective.)
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Root Cause/ Corrective Action
The process requires complete honesty and no
predetermined assumptions.
Follow the Data! Don’t try to lead it.
A common cop-out: “Operator error…”
Why do people not comply?
• Improper instructions
• Worn-out tools
• Improper training
• Lost expectations
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Root Cause/ Corrective Action
Don’t limit the search !
• What role did management systems play?
• Are you looking beyond your own backyard?
• Remember the 80/20 rule.
Be attentive to causes that show up
frequently!
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Root Cause/ Corrective Action
Utilize 5 Why’s technique for determination of
cause and effect… Ask “Why?” 5 times.
Most problems, even the most serious or complex, can be
handled by using the 5 Why technique when coupled with
cause chain diagrams.
So, why use the 5 Why technique?
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Root Cause/ Corrective Action
Just keep asking …
Why did it happen?
•
•
•
•
Didn’t get to work on time.
Car wouldn’t start.
Battery was dead.
Dome light stayed on all night.
……
……
……
……
Why?
Why?
Why?
Why?
Kids played in car, left door ajar.
….. Why?
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Root Cause/ Corrective Action
The 5 Why’s … another example –
Problem: “Customers complain about waiting too long to get
connected to staff during lunch hours.”
Why does the problem happen?
•
Backup operators take longer to connect callers.
Why does it take backup operators longer?
•
Backup operators don’t know the job as well as the regular operator/
receptionist do.
Why don’t backup operators know the job as well?
•
There is no special training, no job aids to make up for the gap in
experience and on-the-job learning for back-ups.
Why don’t they have special training or job aids?
•
In the past, the organization has not recognized this need.
Why hasn’t the organization recognized the need?
•
The organization has no system to identify training needs.
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Decomposition Diagram
• What it is:
– Involves the use of
tree structures to
break down the
area/process under
study
– A tree diagram where
all items are included
(comprehensively
exhaustive) and not
repeated (mutually
exclusive)
Poor
control of
manuf.
process
Don't know
how to
control the
process
Didn't
achieve
spec. first
time
Large volume of
rework in PCB
manufacture
Boards
difficult
to make
They're
designed
like that
The designs
have
been through
several
iterations
• When to use it:
– Can be used as an
analysis structure
Operations
take no
responsibility
for
their work
• Benefits:
– Depicts a single
dimension of
hierarchy
Operators
make
lots of
mistakes
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Operators
poorly
trained?
They rely
upon
100%
inspection
Didn't
understand
implications of
spec.
“Why - Why” (5 Why’s) Analysis
Problem
Why?
Poor control of
manufacturing
process
Large volume of
rework in PCB
manufacture
Boards difficult to
make
Operators make
lots of mistakes
Why?
Why?
Why?
Why?
Don't know how to
control the process
They're designed
like that
The designs have
been through several
iterations
Didn't understand
Didn't achieve spec. implications of spec.
first time
Operators take no
responsibility for their
work
They rely upon
Operators poorly
100% inspection
trained?
… suited to both Repetitive and Non-Repetitive Processes
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“Why - Why” (5 Why’s) Analysis
• What it is:
– A combination of a decomposition diagram and cause and effect diagram in tree
diagram format that shows the linkages between an effect and its root cause
• When to use it:
– When a cause and effect diagram has been built and the primary causes have
been identified, the 5 whys is used to delineate the causal linkages between the
final effect and the originating root cause. ** Don’t be limited to only 5 whys:
the end point is the root cause
• Benefits:
– Establishes the evidence chain (or the hypothesis thereof) so that confirming
facts and data can be collected to substantiate the sequence and the critical
dependencies between relationships and time sequences
– Disciplines the problem solving team to critically examine assumptions and
evidence in order to support the relationships between each link. “How do you
know??”
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Case of a Broken
Photocopier
Why - Why Diagram
Waiting too long
Impatience
Too slow
Wrong machine
Misuse
No budget
Not trained
No plan
No trainer
No plan to replace
MACHINE
BROKEN
No budget
No perceived need
Age
No one responsible
"Old reliable"
Non-business
WHY?
Wrong type machine
Too many copies
Deadlines
Overuse
WHY?
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Not obvious needed
No limits
No one responsible
WHY?
Root Cause/ Corrective Action
Direct Cause: The cause that directly resulted in the
event.
(The first cause in the chain.)
THIS IS THE ANSWER TO YOUR FIRST QUESTION. (YOUR PROBLEM STATEMENT)
Contributing Cause: The cause(s) that contributed to an
event but, by itself, would not have caused the event.
(The cause after the direct cause.)
Note: For a simple problem there may not be any contributing causes.
Root Cause: The fundamental reason for an event,
which if corrected, would prevent recurrence.
(Last cause in the chain.)
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RCCA
Root
Cause
The Cause Chain
Contrib.
Cause
Direct
Cause
Contrib.
Cause
EVENT
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Root Cause Analysis
Let’s expand on a problem … Cause and Effect
Received ticket for safety violation
- Car exhaust too loud
- Muffler knocked loose from tailpipe
- Daughter hit pot hole
- Pot holes in road
- Winters damage roads
- Congress won’t approve extra
money for better roads
- Congress doesn’t have extra money
- Congress spend money on pork barrels
- Too many lawyers in Congress
Solution?
Drive in Sweden, where there are fewer Lawyers.
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Root Cause Analysis
Utilize appropriate toolset with the team.
Uncover the root cause. Test and formulate
corrective action.
Examples:
• Brainstorming, Pareto analysis, Cause and Effect analysis,
X-Y matrix
• Process audit, Benchmarking
• Consensus, mistake proofing (poka-yoke)
• Statistical analysis, quality function deployment
• Opportunity for simplification - Integration and
standardization (refer to VE & VA module)
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Root Cause/ Corrective Action
Corrective Action:
A set of planned activities (actions) implemented for
the sole purpose of permanently resolving the
problem.
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Root Cause/ Corrective Action
Two types of Corrective Action:
• Specific
• Preventive
These two types of corrective action are quite
different in how they are applied and what they do.
Not understanding this leads to serious mistakes in
fixing problems.
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Root Cause/ Corrective Action
Specific Corrective Action:
Action(s) taken to correct the direct cause.
(Corrects, or improves the condition noted in the
event, by changing the direct cause, or the direct
cause and effect.)
• Sometimes called containment
• Only used to correct the DIRECT cause
• Does not prevent recurrence !
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Root Cause/ Corrective Action
Preventive Corrective Action:
• Preventive corrective actions focus on changing
the root cause and any contributing cause(s).
• You probably won’t get a 100% effective fix at
just one point (the root cause).
• You often have to consider two or more
contributing causes to ensure the chain is
broken.
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Root Cause/ Corrective Action
Preventive Corrective Action:
• Action(s) taken prevent recurrence of the
condition noted in the event. (Preventive actions
must directly address the root and contributing
causes to be effective.)
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Preventive Corrective Action
Root
Cause
X
Contrib.
Cause
X
Direct
Cause
Contrib.
Cause
X
EVENT
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Root Cause/ Corrective Action
Test the specific solutions to ensure they
are valid:
• Do the corrective actions eliminate or control the
direct cause?
• Are the results desirable?
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Root Cause/ Corrective Action
Example (ask Team)
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Root Cause/ Corrective Action
Preventive Action Test:
• If these preventive corrective actions were in
place, would the event have occurred?
• Are there adverse effects caused by
implementing the corrective actions that make
them undesirable?
• Do the preventive corrective actions lower the
risk factor of the event to an acceptable level?
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Root Cause/ Corrective Action
Basic elements of reporting:
•
•
•
•
•
•
Restatement of the problem/ event/ objective
Data (who, what, where, why, how, etc.)
Team (natural work group, qualified)
Causes (root, direct, contributing)
Corrective Actions (specific, preventive, plant-wide)
Milestone dates (Analysis complete, C/A initiated,
C/A implemented, Corrective Action Report closed)
• Follow Up (Is implementation, solution acceptable?)
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Tracking Form - example
Basic tracking form –
Corrective Action Matrix (CAM)
Refer to - webpage (tools)
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Tracking Form - example
NOTE: Blank form located on free lean site
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Root Cause/ Corrective Action
Follow-up
A review must be conducted in sufficient detail to
assess whether the corrective actions that
have been implemented are effective as
implemented and are truly preventing
recurrence of the event.
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Root Cause/ Corrective Action
Effectiveness Measures
The criteria used to evaluate if the corrective
actions achieved the desired outcome.
Examples:
•
•
•
•
Scrap quantities significantly reduced
Print was not manufactured to print tolerance. After corrective action,
part meets print.
Design could not be manufactured with current technology. After
corrective action, part can be manufactured with current technology.
Parts would not assemble properly. After corrective action, parts
would assemble properly.
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Root Cause/ Corrective Action
Did corrective actions work?
Some additional things to consider:
•
•
•
•
If corrective action implemented differs from proposed,
find out why.
If better or alternate corrective actions were implemented, document
the changes.
Periodic checks may be necessary to be sure the corrective actions
are still in place.
Document using the proper forms.
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Root Cause Analysis - Overview
Root Cause Analysis
and
Corrective Action (RCCA)
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