Root Cause Analysis: Why? Why? Why?

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Root Cause AnalysisWhy? Why? Why?

• William A. Lindley
• April 6, 2001

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Why Do Root Cause Analysis?

• Just fix it, there is too much to do.
• We dont have time to think, we need results
  now.
• Reality - fix symptoms without regard to actual
  causes
• Root Cause Analysis - structured and thorough
  review of problem designed to identify and verify
  what is causing the symptoms

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Definitions

• Cause (causal factor) a condition or event that
  results in an effect
• Direct Cause cause that directly resulted in the
  occurrence
• Contributing Cause a cause that contributed to
  the occurrence, but by itself would not have
  caused the occurrence
• Root Cause cause that, if corrected, would
  prevent recurrence of this and similar
  occurrences

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How Is Root Cause Analysis Done?

• Teams identify all possible causes
• The actual root causes are identified and
  verified
• Corrective action(s) are identified to reduce or
  eliminate the problem

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RCA Process
Relationship between cause and effect

• Need for creative thought to identify all
  possible causes
• Collect data about the problem
• Analyze data
• Verify causes

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Root Cause Tools

• Cause and Effect Diagram
• Scatter Diagram - prove cause-effect relationship
• Control Chart - process stable?
• Five Whys
• Tree Diagram
• Change Analysis
• Barrier Analysis
• Event and Causal Factor Analysis
• Management Oversight Risk Tree Analysis (MORT)

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Cause Effect Diagram

• Visual display of possible causes
• Cause categories include materials, machines,
  methods, and people
• Reveals gaps in existing knowledge
• Helps team reach common understanding of why loss
  exists

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Cause Effect Diagram
People
Procedures
Problem
Equipment
Materials
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Cause Effect Diagram

• Danger
• The Cause Effect Diagram is a list of potential
  root causes. This includes both probable causes,
  real causes and guesses.

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After The Cause Effect Diagram

• Identify likely candidates for root cause(s) by
  one of the following actions
• Look for causes that appear repeatedly within or
  across major cause or process categories
• Look for changes or other sources of variation in
  the process or environment
• Use consensus decision-making to select
• Collect data to confirm a potential root cause as
  real

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Scatter Diagram

• Test for possible cause and effect relationships
• Some variation should be expected
• Relationships being tested must be logical
• Visual depiction of relationship

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Patterns of Correlation
Quality Improvement Tools Juran Institute, 1989
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Correlation Coefficients
Quality Improvement Tools Juran Institute, 1989
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Scatter Diagram
Data shows strong positive correlation.
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Statistical Process Control

• Process Variation - Common Cause Special Cause
• Is the process stable?
• Points outside LCL/UCL warrant investigation
• Alert for problems

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Five Whys

• Describe the problem in specific terms
• For each likely cause ask, Why did this happen?
• Continue for a minimum of five times
• Show logical relationship of each response to the
  one that preceded it
• Stop when the team has enough information to
  identify the root cause

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Tree Diagram

• State the problem
• Causes are listed as branches to the right of the
  problem
• Continue to clarify causes, drawing additional
  branches to the right
• Repeat until each branch reaches its logical end

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Tree Diagram Example
Too much work
Not enough students signed up
No reward
Schedule not communicated
No time to learn
Trainer not prepared
New trainer assigned late
Training Class Cancelled
Turnover
Flexibility
Materials not completed
Changes up to class date
Late changes
Current
Floating due date
Training Dept - other projects
This project- low priority
More info needed
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Cautionary Note

• Its impossible to solve significant problems
  using the same level of knowledge that created
  them!
• Albert Einstein

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Cautionary Note - Part 2

• Cause and effect analysis cant get past existing
  knowledge - must have either observed (or
  considered) that the cause produced the effect in
  the past

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Why not just ask Why?

• Need to systematically organize and analyze data
• First understand What happened then Why
• Typically multiple root causes
• Blame is an obstacle
• Guidance needed to investigate human performance
  problems
• Need to ask right questions to completely
  understand why
• Some RCA techniques may provide easy answers that
  are either incomplete or wrong (but easy to find)

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Event and Causal Factor Analysis

• Used for multi-faceted problems or long, complex
  causal factor chains
• Cause effect diagram that describes time sequence
• Anything that shapes the outcome recorded
• Identifies what questions to ask to follow path
  to root cause

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Event and Causal Factor Analysis
Condition
Condition
Condition
Condition
Condition
Conditions that may exist, but not identified
Condition
Condition
Condition
Found or existing state that influences outcome
Event
Potential Event
Event
Event
Sequence of happenings
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Change Analysis

• Used when problem is obscure
• Generally used for single occurrence
• Focuses on things that have changed
• Compares trouble-free process with occurrence to
  identify differences
• Differences evaluated for contribution to
  occurrence

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Change Analysis Steps
Occurrence with undesirable consequence
1
5
4
Analyze differences for effect on
undesired consequences
Identify differences
3
Compare
Integrate information relevant to the causes of
undesired consequence
Comparable activity without undesired result
2
6
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Change Analysis Steps

• Answer the following
• What?
• When?
• Where?
• How?
• Who?

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Barrier Analysis

• Systematic process to identify barriers or
  controls that could have prevented the occurrence
• Physical
• Administrative
• Procedural
• Determine why these barriers or controls failed
• What is needed to prevent reoccurrence

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Barrier Analysis
Sequence of events
Electricians Follow Procedure
System Tagout
Tag Hung
Electricians Given Assignment
Reactor Trip
Barriers Analysis
Tagout Process Step 1
Tagout Process Step 2
Communications Process Interface
Start
Procedure
Occurrence
Barrier Holds
Barrier Holds
Barrier Holds
Barrier Fails
Barrier Fails
Barrier Fails
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Management Oversight and Risk Tree (MORT)

• Used to prevent oversight in the identification
  of causal factors
• Specific factors listed
• Management factors that permit these factors to
  exist listed
• Questions for each factor on the tree are included

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