1. Session 10: Cause and Effect
Idea Diagrams:
Cause and Effect, Affinity and
Tree Diagrams
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Seven Basic Quality Tools
1. Process Mapping / Flow Charts*
2. Check Sheets
3. Pareto Analysis
4. Cause & Effect Diagrams
5. Histograms
6. Scatter Diagrams (XY Graph)
7. Control Charts
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Six Sigma Greenbelt: University of Michigan

2. Session 10: Cause and Effect
Topics
I. Cause and Effect Diagrams
A. Ishikawa Fishbone Diagram
B. Failure Mode Cause and Effect Diagram
II. Affinity Diagram
III. Tree Diagram
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I. Cause-and-Effect Diagrams
Cause-and-Effect Diagrams are used to:
visually identify potential causes of problems.
organize cause-and-effect relationships.
assist in root cause analysis.
demonstrate knowledge of problem-solving team.
Two Common Formats:
A. Ishikawa (Fishbone) Diagram
B. Failure Mode Cause-and-Effect Diagram
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Six Sigma Greenbelt: University of Michigan

3. Session 10: Cause and Effect
A. Cause & Effect Diagram
(Ishikawa or Fishbone Diagram)
Cause Branch Effect – failure
twig Branch – Main Categories
(Example: 4M’s - man, method,
twiglet
machine, material)
Effect
Twig – 1st Level Causes
Twiglets – 2nd Level Causes
causes effect
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Cause-and-Effect Diagrams
Classification headings in cause-and-effect diagrams often
are derived from qualitative process analysis.
4M’s (5 or 6 M’s)
Man (personnel), Method, Machine, Material
Measurement system (or, include with machine)
Mother nature – uncontrollable external issues
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Six Sigma Greenbelt: University of Michigan

4. Session 10: Cause and Effect
Cause and Effect Analysis
Construct the cause and effect diagram as the
basis of analysis.
Do not stop until you reach root causes (not
symptoms).
Ask questions and question assumptions.
Do not jump to “The Solution.”
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Constructing a Cause and
Effect Diagram
Decide the problem to be analyzed.
Draw and label the effect line.
Draw and label the cause branches (e.g., 4M’s).
Ask “why” problem occurs to determine first level
causes
Continue to determine the next level of causes. Try
not to stop until you reach root causes (vs.
symptoms).
Highlight likely root causes.
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Six Sigma Greenbelt: University of Michigan

5. Session 10: Cause and Effect
Creating a Cause and Effect
Diagram
Effect
Effect - failure
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Elements of a Cause and Effect
Diagram
Man Method
Effect
Branch - broad
categories,
i.e. 4 M’s
Machine Material
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Six Sigma Greenbelt: University of Michigan

6. Session 10: Cause and Effect
Elements of a Cause and Effect
Diagram
Man Method
1st Level Cause
Effect
Twig - 1st Level Cause
Machine Material
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Elements of a Cause and Effect
Diagram
Man Method
2nd Level Cause
Effect
Machine Material
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Six Sigma Greenbelt: University of Michigan

7. Session 10: Cause and Effect
Lecture Exercise: Create a
Cause and Effect Diagram
Create a Cause and Effect Diagram for the
following problem:
Effect: customer dissatisfaction for delayed airline
flight departures
Use the following Cause Branches:
Machine (Equipment); Man (Personnel); Method;
Materials; Environment
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Lecture Exercise: Machine
Machine Gate
not
Mechanical working
Flight
Delays
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Six Sigma Greenbelt: University of Michigan

8. Session 10: Cause and Effect
Lecture Exercise: Man
Machine Gate Man
not Late
Mechanical working Crew
Late Cleaning
Pilot Late
Flight
Delays
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Lecture Exercise: Method
Machine Gate Man
not Late
Mechanical working Crew
Late Cleaning
Pilot Late
Flight
Delays
Gate
Boarding
blocked
Process
Unclear
Procedure
Method
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Six Sigma Greenbelt: University of Michigan

9. Session 10: Cause and Effect
Lecture Exercise: Materials
Machine Gate Man
not Late
Mechanical working Crew
Late Cleaning
Pilot Late
Flight
Delays
Late
Late Meals
Baggage Gate
Boarding
blocked
Process
Unclear
Late Procedure
Materials Method
Fuel
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Lecture Exercise: Environment
Machine Gate Man
not Late
Mechanical working Crew
Late Cleaning
Environment Pilot Late
Weather FAA Delay Flight
Delays
Late
Late Meals
Baggage Gate
Boarding
blocked
Process
Unclear
Late Procedure
Materials Method
Fuel
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Six Sigma Greenbelt: University of Michigan

10. Session 10: Cause and Effect
B. Failure Mode Cause-and-Effect
Diagram
Methods
Note: may have multiple effects,
Machinery and/or multiple causes
Downstream End-user
Material Failure Process Operation
Mode
Man (Person)
Environment
Causes ||| Effects 19
Failure Mode Cause-and-Effect
Diagram (Airline Example)
Man
Late Crew
Method
Boarding
Process
Failure
Equipment Mode Customer Missing Lost
Dissatisfaction Connections Profits
Gate Not
Working
Material
Late Fuel Flight Does Not Leave On-Time
Late Baggage
Environment
Severe Weather
Causes ||| Effects 20
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Six Sigma Greenbelt: University of Michigan

11. Session 10: Cause and Effect
II. Affinity Diagram
Affinity – “natural attraction”
Brainstorming technique used to gather and group
ideas.
Useful for analyzing causes of quality problems, survey
analysis, customer complaints.
Basic premise –
while numerous reasons may exist for a problem, they are
usually grouped around some common themes. And, by
identifying these common themes, a team can better focus on
finding root causes and implementing multilateral
recommendations.
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Constructing Affinity Diagrams
for Six Sigma Projects
Basic Steps:
Select a problem.
Identify causes via brainstorming or interviews.
Write each cause on a note card or Post-It (each cause should
be 2-7 words)
Examine causes and cluster them into groups (usually in
silence).
Review the clusters and decide on best grouping.
Use final grouping to generate additional causes.
Develop a plan to address major groupings or potential root
causes.
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Six Sigma Greenbelt: University of Michigan

12. Session 10: Cause and Effect
Example: Software Re-Design
Project
Six Sigma Project
Problem: employees are complaining about the limitations of an
internally developed excel-based program used in the Production
Part Approval Process.
Software Product – provides a statistical summary of the part
characteristics to verify production readiness.
Six Sigma Team was formed to identify causes of the complaints.
Team interviewed various users for input. Can you think of any
likely concerns based on past experience?
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Exercise: Affinity Diagram
(create 2-4 groupings of concerns)
1. Difficult to navigate
2. No standardized summary reports
3. Limited graphical summary reports
4. Cannot analyze multiple characteristics
5. Difficult to change part specifications
6. Cannot handle blank cells within data range
7. Few user friendly features
8. Difficult to import/export data
9. No formula protection
10. No outlier analysis
11. Takes too long to setup print feature
12. Data Files too big (programming in every file)
13. Too much manual input
14. No customized features to perform analysis
15. No customized naming of files
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Six Sigma Greenbelt: University of Michigan

13. Session 10: Cause and Effect
Groupings
Suppose the team has identified 3 Groupings for the
concerns.
Place the previous concerns into the following:
A. Data Analysis Capability
B. Functionality – Ease of Use
C. Programming Efficiency
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Affinity Diagram –
Production Part Approval Software
A. Data Analysis Capability
B. Functionality – Ease of Use
Limited graphical summary reports
Difficult to navigate
Cannot analyze multiple characteristics
Few user friendly features
Difficult to change part specifications
Takes too long to setup print feature
No standardized summary reports
Too much manual input
No outlier analysis
No customized naming of files
No customized features to perform analysis
C. Programming Efficiency
Cannot handle blank cells within data range
Difficult to import/export data
No formula protection
Data Files too big (programming in every file)
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Six Sigma Greenbelt: University of Michigan

14. Session 10: Cause and Effect
Affinity Diagram – Next Steps
After grouping all of the data, you should brainstorm for
additional causes / concerns. (Grouping – generate
more ideas)
Case Study –
For this case study, a list of recommendations were developed to
improve the software tool including converting the tool into a read-
only application.
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III. Tree Diagram
A tree diagram provides a hierarchy of cause-effect
relationships.
Often need to keep asking why to better understand
root cause(s) of problems.
Cause
…
Cause
Cause
Problem
Cause …
Cause Cause
….
WHY? 28
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Six Sigma Greenbelt: University of Michigan

15. Session 10: Cause and Effect
Tree Diagram Example:
Loan Case Study Why?
Loan takes too long Internal processing errors Loan application
errors from customer Loan officers do not know all the details to
obtain for a lending program Branch Managers do not provide
standard guidelines of lender programs Central office does not
provide branch managers with support to develop standards.
Loan Application
Internal Errors
Processing
Errors
Loan take Lender Program changes
Too long
Loan Application Errors
To process
Underwriting Delays waiting for external
Delays Underwriter to process loan
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Tree Diagram – Alternative Use
Tree Diagrams also may be used in the IMPROVE
PHASE to identify ways or means to complete a task
or objective.
Means
…
Means
Means
Objective
Means …
Means Means
….
How?
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Six Sigma Greenbelt: University of Michigan