Cause and Effect
Analysis:
1. Fishbone Diagram
2. Cause and Effect Matrix
1
Cause and Effect Analysis
Learning Objectives

Define the relationship between Cause and
Effect

Explain use and construction of:

Fishbone Diagram



Guidelines for Brainstorming
Cause and Effect Matrix
Learn how to integrate Fishbone Diagram and
Cause & Effect Matrix into your Company
SOPs
2
Cause and Effect Analysis
What do you mean by “ Cause & Effect”?
A PROBLEM WHICH
HAS OCCURED
A POTENTIAL
FUTURE PROBLEM
(FMEA)
CAUSE
EFFECT
CAUSE
Events/conditions Symptoms that
provide evidence
that led to
of the problem
the problem
Events/conditions
that would lead to
the problem
EFFECT
Symptoms that
would result
from the problem
Dave Wessel, “An Ounce of Prevention”, Quality Progress, Dec, 1998
3
Cause and Effect Analysis
Cause - Effect Relationship
A PROBLEM WHICH
HAS OCCURED
CAUSE
EFFECT
Events/conditions
that led to
the problem
Symptoms that
provide evidence
of the problem
ACTION
Dave Wessel, “An Ounce of Prevention”, Quality Progress, Dec, 1998
4
Fishbone
Diagram
5
Cause and Effect Analysis
What is a Fishbone Diagram?
A visual tool used to identify, explore and
graphically display all the possible causes related
to a problem to discover root causes.
A Fishbone diagram is also known as a Cause
and Effect Diagram or Ishikawa Diagram.
Materials
C/N/X
Methods
C
C
N
N
N
N
N
C
C
C
Machinery
Problem/
Desired
Improvement
Manpower
6
Cause and Effect Analysis
Dr Kaoru Ishikawa







Quality control statistician
Professor in University of Tokyo
One of the pioneers of Japan’s quality
revolution in the 1940s
Played major role in growth of QC
circles
Best known for formalizing use of
Cause-and-Effect Diagram
Won the Deming Prize and Shewhart
Medal
ASQ established the Ishikawa Medal to
recognize the human side of quality
7
Cause and Effect Analysis
Why Use Fishbone Diagrams?
 To discover the most probable causes to a
problem (or effect)
– Sometimes, the effect can be a desirable effect.
– When something desirable has happened, it is
useful to find out what caused it so that you can
make it happen again
 To visual possible relationships between causes
for a given problem under investigation
8
Cause and Effect Analysis
Constructing a Fishbone Diagram
1. Establish what the problem (effect) is
 It must be stated in clear and concise terms,
agreed by everyone.
2. Write the effect on the head of the fish
3. Decide the major categories of causes
 Brainstorming
 Use standard categories such as 5M+E
(Machines, Materials, Methods, Manpower,
Measurement & Environment)
 Use major steps in the process if the effect is
resulted from a recognizable process
• See example????
Let’s create a Fishbone Diagram using Minitab
9
Cause and Effect Analysis
Constructing a Fishbone Diagram
Stat Quality Tools Cause-and-Effect
10
Cause and Effect Analysis
Constructing a Fishbone Diagram
Fishbone Diagram for Surface Flaws
Measurements
Materials
Man
List specific
causes in each
category
Surface Flaws
Environment
Methods
Machines
Problem (effect)
at the “head of
the fish”
Major categories of causes
(or sometimes call major bones)
Why do we need to group the causes?
11
Cause and Effect Analysis
Constructing a Fishbone Diagram
4. Identify possible causes through Brainstorming
• Identify specific causes within each major category that
may be affecting the problem.
Fishbone Diagram for Surface Flaws
Measurements
3. Continue
asking: ‘Why is
this happening?’
until you no
longer get useful
information.
Micrometers
Materials
Calibration Method
Calibration Interval
Precision
Accuracy
Personnel
Alloys
Lubricants
Supervisors
Suppliers
Microscopes
2. Repeat this
procedure with each
specific cause to
produce sub-causes.
Shifts
Training
Operators
Inspectors
Surface Flaws
Speed
Brake
Machine feedrate
Machine rpm
Lathes
Brand of bit
Condensation
Moisture%
Environment
Engager
Bits
Angle
Methods
Sockets
Machines
Size of bit
1. The team should ask :
‘What are the machine
issues affecting/causing
the problem?’
When do we know we have reached the root cause ?
12
Cause and Effect Analysis
Analyzing a Fishbone Diagram
5. When brainstorming session is completed, every
cause should be labeled as either a “C”, “N” or “X”.
C
variables that must be held as constant as possible
and require standard operating procedures to insure
consistency
N
variables that are noise or uncontrolled variables and
cannot be cheaply/easily held constant
X
variables considered to be KPIVs and need to be
experimented to determine what influence each has
on the output and what their optimal settings should
be to achieve customer-desired performance
13
Cause and Effect Analysis
Analyzing a Fishbone Diagram
6. The team should analyze and zoom in those
“most likely causes”.
Helpful Hint
Look out for causes that appear in more than one
category. They may be the “most likely causes”.
7. The most likely causes should be prioritized
for further investigation.
14
Cause and Effect Analysis
Integrating Fishbone Diagram into SOPs
Example of how fishbone diagram can be used in SCAR.
Section of SCAR Procedure
Fishbone diagram can be
used here to brainstorm/
identify root causes
Received
complaint/reject
from customer, inhouse or supplier.
QA personnel verify
the defects.
Issue CAR to
production.
Purge in-house
stock
Should also
update Fishbone
diagram
1. Fishbone diagram can be used here to
brainstorm/ identify root causes.
2. To prioritize and work on most likely
causes.
15
Hold meeting with
relevant
departments (if
necessary)
Generate
report for
management
review
Follow up on
CAR
-receive CAR
reply from
production
- reply to
customer
Cause and Effect Analysis
Integrating Fishbone Diagram into SOPs
Example of how fishbone diagram can be used in SPC control
Section of SPC Control Procedure
5.4.2.4 It is the responsibility of the EA of CMM section to set-up the trend-tests for
out-of-control in the "SPC" software.
5.4.2.5 The E.A/Supervisor of the 'CMM' section shall monitor the X-R Charts on the
computer and look-out for out-of-control situation. When out-of-control is detected,
he shall analyse the subgroup data, the histogram and the prevailing Cpk value,
based on these he shall decide the action to take. When the situation necessitates,
a "PCAR" shall be issued to the Production E.A/Supervisor.
5.4.2.6 The Production Supervisor/E.A shall analyze the problem and take corrective
actions on the process concerned, after which, new samples shall be submitted
for measurement. When the problem has been rectified, Production Supervisor/EA
shall write in the "PCAR" form, the corrective actions taken and return the form to
the E.A or Supervisor of "CMM" section.
Fishbone diagram can be used here to
brainstorm/ identify root causes
16
Cause and Effect Analysis
Link Tools Integration Tasks to Work
Breakdown Structure
The effort to integrate Fishbone Diagram into
SPC and SCAR procedures should be translated
into specific tasks in the Work Breakdown
Structure.
S/N
Tasks
Task Owner
Target
Completion Date
Specific Training
needed for Task
Owner/ Date
Core Team
Member In
Charge
Internal Verified
Date
Group Phase
End Date
James
10-Dec-01
Fishbone Diagram
-15 Oct 2001
Nick
15-Dec-01
31-Dec-01
Harry
10-Dec-01
Fishbone Diagram
- 15 Oct 2001
Nick
15-Dec-01
31-Dec-01
Group 1 Tools
1
SPC
Integrate Fishbone
Diagram in the SPC
procedure/system
2
SCAR
Integrate Fishbone
Diagram in the SCAR
procedure/system
17
Cause & Effect
Matrix
18
Cause and Effect Analysis
Cause and Effect Matrix
Cause and Effect
Matrix
Process Step
7
8
9
Requirement
Requirement
Requirement
Requirement
Requirement
Requirement
Requirement
Requirement
10
11
12
13
14
15
Requirement
6
Requirement
5
Requirement
4
Requirement
3
Requirement
2
Requirement
1
Requirement
Rating of
Importance to
Customer
Total
Process Input
Lower Spec
Target
Upper Spec
19
0
0
0
0
0
0
0
0
0
0
0
0
0
Total
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Cause and Effect Analysis
Description: Cause and Effects Matrix




Simple QFD (Quality Function Deployment) matrix.
Used to relate and prioritize X’s to customer Y’s through
numerical ranking using the process map as the
primary source.
Y’s are scored as importance to the customer
X’s are scored as to relationship to outputs
Results



Pareto of Key Inputs to evaluate in the FMEA and Control Plans
Input into the Capability Study
Input into the initial evaluation of the Process Control Plan

This is the team’s first stab at determining Y = f(X)
20
Cause and Effect Analysis
Constructing a Cause & Effect Matrix
1. List key outputs (Y’s)
Cause and Effect
Matrix
2
3
4
5
6
7
8
Viscosity
Cleanliness
Color
Homogeneity
Consistency
Temperature
Solids
Process Inputs
1
Gel Time
Rating of
Importance
to Customer
1
2
3
4
5
6
7
9
10
11
12
13
14
15
Total
0
0
0
0
0
0
0
21
Cause and Effect Analysis
Constructing a Cause & Effect Matrix
2. Rank Y’s with respect to customer importance
9
7
10
10
9
3
2
6
1
2
3
4
5
6
7
8
9
Cleanliness
Color
Homogeneity
Consistency
Digets Time
Temperature
Solids
Process Inputs
9
Viscosity
Rating of
Importance to
Customer
Gel Time
Cause and Effect
Matrix
1
2
3
4
5
6
7
8
10
11
12
13
14
15
Total
0
0
0
0
0
0
0
0
22
Cause and Effect Analysis
Constructing a Cause & Effect Matrix
1
2
3
4
5
6
7
8
9
7
10
10
9
3
2
6
1
2
3
4
5
6
7
8
9
Color
Homogeneity
Consistency
Digets Time
Temperature
Solids
Process Inputs
9
Cleanliness
Input
Variables
9
Viscosity
Rating of
Importance to
Customer
Gel Time
3. List key inputs (X’s)
Scales
Accuracy
Preheating
DICY TK
DMF Load
Accuracy
DMF
Cleanliness
DMF Raw
Materials
DICY Load
Accuracy
DICY Envir.
Factors
DICY Raw
Materials
DICY Mixer
Speecd
10
11
12
13
14
15
Total
0
0
0
0
0
0
0
0
0
23
Cause and Effect Analysis
Constructing a Cause & Effect Matrix
 You are ready to correlate customer
requirements to the process input variables
 Avoid confusion and inconsistency by
establishing scoring criteria:
0 = no correlation
1 = the process effect only remotely affects the
customer requirement
4 = The input variable has a moderate effect on
the customer requirement
9 = The input variable has a direct and strong
effect on the customer requirements
Note: Not recommended to use more than 5 different criteria.
24
Cause and Effect Analysis
Constructing a Cause & Effect Matrix
4. Relate X’s to Y’s
7
8
9
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Solids
6
2
Temperature
5
2
Digets Time
4
9
Consistency
3
10
Homogeneity
2
Scales
Accuracy
Preheating
DICY TK
DMF Load
Accuracy
DMF
Cleanliness
DMF Raw
Materials
DICY Load
Accuracy
DICY Envir.
Factors
DICY Raw
Materials
DICY Mixer
Speecd
10
Color
1
9
Cleanliness
Process Inputs
9
Viscosity
X’s
9
Gel Time
Rating of
Importance to
Customer
9
9
3
1
1
9
1
1
9
348
1
1
1
1
1
1
1
1
1
66
3
9
1
1
1
9
1
3
9
255
1
1
5
1
1
1
1
1
1
102
1
1
1
1
1
1
1
1
1
66
9
9
1
1
1
9
1
1
1
282
9
5
3
1
1
9
1
1
1
247
8
5
1
1
1
9
1
1
2
242
1
1
1
1
7
1
1
1
1
126
25
Y’s
Total
Cause and Effect Analysis
Constructing a Cause & Effect Matrix
5. Cross-multiply and add
8
9
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Solids
7
2
Temperature
6
2
Digets Time
5
9
Consistency
4
10
Homogeneity
3
10
Color
2
Scales
Accuracy
Preheating
DICY TK
DMF Load
Accuracy
DMF
Cleanliness
DMF Raw
Materials
DICY Load
Accuracy
DICY Envir.
Factors
DICY Raw
Materials
DICY Mixer
Speecd
9
Cleanliness
1
9
Viscosity
Process Inputs
9
Gel Time
Rating of
Importance to
Customer
9
9
3
1
1
9
1
1
9
348
1
1
1
1
1
1
1
1
1
66
3
9
1
1
1
9
1
3
1
1
5
1
1
1
1
1
1
1
1
1
1
1
1
1
9
9
1
1
1
9
1
1
9
5
3
1
1
9
1
1
1
247
8
5
1
1
1
9
1
1
2
242
1
1
1
1
7
1
1
1
1
126
26
Total
9
Key
inputs are now
1
ranked
in importance
with
respect to the
1
key
outputs
1
So??
255
102
66
282
Cause and Effect Analysis
How Cause & Effect can Fit into Process
Improvement Activities
C&E Matrix
7
8
9
2
6
7
8
9
10
11
12
13
14
15
Solids
6
3
6
Temperature
5
9
5
Digets Time
4
10
4
Consistency
3
10
3
Homogeneity
2
Scales
Accuracy
Preheating
DICY TK
DMF Load
Accuracy
DMF
Cleanliness
DMF Raw
Materials
DICY Load
Accuracy
DICY Envir.
Factors
DICY Raw
Materials
DICY Mixer
Speecd
7
2
Color
1
9
1
Cleanliness
Process Inputs
9
Viscosity
Rating of
Importance to
Customer
Gel Time
The Big Picture
9
8
2
1
1
9
1
1
8
1
1
1
1
1
1
1
1
1
65
3
8
1
1
1
8
1
3
8
255
1
1
4
2
1
2
1
1
1
105
1
1
1
1
1
2
1
1
1
74
9
7
1
1
1
9
1
1
2
269
8
5
3
1
1
8
1
1
2
247
8
5
1
1
1
9
1
1
2
242
1
1
1
1
7
1
1
1
1
125
Total
321
Control Plan Summary
Capability Summary
Operational Excellence
Control Plan
Key Process Output Variable
Capability Status Sheet
Customer Requirement
(Output Variable)
Measurement
Technique
%R&R or P/T
Ratio
Upper
Spec
Limit
Target
Lower
Spec
Limit
FMEA
Cp
Cpk
Sample
Size
Date
Product:
Key Contact:
Phone:
Process
Actions
Gel Time
Viscosity
Cleanliness
Color
Homogeneity
Consistency
Digets Time
Temperature
Solids
DICY
Process/Product
Failure Modes and Effects Analysis
(FMEA)
The Key Outputs are
evaluated ability to meet
customer spec.
Process or
Product Name:
Prepared by:
Responsible:
FMEA Date (Orig) ______________ (Rev) _____________
Process
Step/Part
Number
Spin Draw
Process
Potential Failure Mode
Fiber Breakouts
Potential Failure Effects
Undersized package, High SD
panel-hours lost
S
E
V
Potential Causes
Dirty Spinneret
2
O
C
C
8
Filament motion
5
Current Controls
Visual Detection of Wraps and
broken Filaments
D
E
T
R
P
N
9
144
Core Team:
Date (Rev):
Process Step
Input
Output
Process
Specification (LSL,
USL, Target)
Cpk /Date
Measurement
Technique
%R&R
P/T
Sample
Size
Sample
Frequency
Control
Method
Reaction Plan
Turn Steam on Scales
Accuracy
DMF
Load DMF
DMF Load
Accuracy
DMF
Load DMF
DMF
Cleanliness
DICY
Load DICY
DICY Envir.
Factors
DICY
Load DICY
DICY Load
Accuracy
DICY
Load DICY
DICY Raw
Materials
DICY
Load DICY
DICY Mixer
Speecd
DMF
Load DMF
DMF Raw
Materials
DICY
Date (Orig):
Turn Steam on Preheating
DICY TK
Visual Sight-glass
2
8
80
9
144
The Key Inputs are
evaluated for process
control
Key Inputs are explored while evaluating
process for potential failure
Polymer defects
8
Fuzzball Light
2
0
27
Cause and Effect Analysis
Integrating Cause & Effect Matrix into SOPs
Example of how Cause and Effect Matrix can be used in SCAR.
Section of SCAR Procedure
Cause and Effect Matrix can be
used in conjunction with fishbone
diagram to identify, rank and
prioritize the key causes.
Received
complaint/reject
from customer, inhouse or supplier.
QA personnel verify
the defects.
Issue CAR to
production.
Purge in-house
stock
Cause and Effect Matrix can be
used in conjunction with fishbone
diagram to identify, rank and
prioritize the key causes.
28
Hold meeting with
relevant
departments (if
necessary)
Generate
report for
management
review
Follow up on
CAR
-receive CAR
reply from
production
- reply to
customer
Cause and Effect Analysis
Integrating Cause & Effect Matrix into SOPs
Example of how Cause & Effect Matrix can be used in SPC control
Section of SPC Control Procedure
5.4.2.4 It is the responsibility of the EA of CMM section to set-up the trend-tests for
out-of-control in the "SPC" software.
5.4.2.5 The E.A/Supervisor of the 'CMM' section shall monitor the X-R Charts on the
computer and look-out for out-of-control situation. When out-of-control is detected,
he shall analyse the subgroup data, the histogram and the prevailing Cpk value,
based on these he shall decide the action to take. When the situation necessitates,
a "PCAR" shall be issued to the Production E.A/Supervisor.
5.4.2.6 The Production Supervisor/E.A shall analyze the problem and take corrective
actions on the process concerned, after which, new samples shall be submitted
for measurement. When the problem has been rectified, Production Supervisor/EA
shall write in the "PCAR" form, the corrective actions taken and return the form to
the E.A or Supervisor of "CMM" section.
Cause and Effect Matrix can be
used in conjunction with fishbone
diagram to identify, rank and
prioritize the key causes.
29
Cause and Effect Analysis
Link Tools Integration Tasks to Work
Breakdown Structure
The effort to integrate Cause & Effect Matrix into
SPC and SCAR procedures should be translated
into specific tasks in the Work Breakdown
Structure.
S/N
Tasks
Task Owner
Target
Completion Date
Specific Training
needed for Task
Owner/ Date
Core Team
Member In
Charge
Internal Verified
Date
Group Phase
End Date
Dick
10-Dec-01
Fishbone Diagram
-15 Oct 2001
Cause & Effect
Matrix
-15 Oct 2001
Nick
15-Dec-01
31-Dec-01
Mary
10-Dec-01
Fishbone Diagram
-15 Oct 2001
Cause & Effect
Matrix
-15 Oct 2001
Nick
15-Dec-01
31-Dec-01
Group 1 Tools
1
SPC
Integrate Cause and
Effect Matrix in the
SPC procedure/ system
2
SCAR
Integrate Cause and
Effect Matrix in the
SCAR procedure/
system
30
Cause and Effect Analysis
End of Topic
Any question?
31
Cause and Effect Analysis
Product/Manufacturing Example
Measurement
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Machine
Settling of Slurry
Particles (C)
Slurry Flow Rate (C)
Ra (C)
Line Density (C)
Texture
Temperature (C)
Material
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Program used (N)
Skew (N)
PU Pad (C)
Sonic power (C)
Texture
Temperature (C)
Calibration (N)
Slurry Type (C)
Substrate (C)
Tape Type (C)
Surfactant Type (C)
PU Pad (C)
NLA
Method
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Settling of Particles (C)
Slurry Stirring Procedures (C)
Program used (N)
Speed Adjustment (C)
Ultrasonic on/off (C)
Soak Time (C)
Stagging Time (N)
Transfer Time (C)
Texture Temperature (C)
Concentration of Chemica (C)
Tape Speed (C)
Slurry Flow Rate (C)
Texture Pressure (C)
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Man
32
Slurry Stirring Procedure (C)
Soak Time (C)
Stagging Time (N)
Transfer Time (C)
Compliance to Procedures (C)
Cause and Effect Analysis
Transactional Example
Estimated Ship Date Change - CAUSE & EFFECT / FISHBONE
MDC
PRACTICES
SCHEDULE
CHANGES
ORDER
CANCELLATION
- Firm
- Planned
MDC
CAPACITY
- B.O.. Consol.
- SC late
WCSC
PRACTICES
- Receiving
- Picking
- PC delays
- Off shift support
- Unrealistic
Del. Req
Dates
- Customer Order
Priority Changes
Estimated
Ship Date
Changes
- Bad IT days
- Table Maint.
- Waiting for
Delivery Appt.
IN
TRANSIT
TIMES
- Availability
Overrides
- No Stocks
INVENTORY
ACCURACY
APPOINTMENT
CUSTOMER
PLANNED
SHIP DATE
ALGORITHM
- Late PT print
- Late EDI data
LDSS
33
- No Delivery Constraints
After initial PSD
- Back Ord. Release Logic
- Cust Priority vs. availability
-Future orders at AP
ESD
ALGORITHM
ANOMALIES
Brainstorming
?
?
?
?
?
?
A technique to
generate a large
number of ideas or
possibilities in a
relatively short time
frame.
Why Use Brainstorming?
• A tool for the Team (not individual)
• A method to generate a lot of ideas
• Two persons’ knowledge and ideas are
always more than an individual’s
• Input for other C&E tools
• Active participation
34
Cause and Effect Analysis
How to Conduct a Brainstorming Session
Team Makeup
 Experts
 “Semi” experts
 Implementers
 Analysts
 Technical staff who will run the experiment
 Operators
Discussion Rules
 Suspend judgement
 Strive for quantity
 Generate wild ideas
 Build on the ideas of others
Leader’s rules for Brainstorming
 Be enthusiastic
 Capture all the ideas
 Make sure you have a good skills mix
 Push for quantity
 Strictly enforce the rules
 Keep intensity high
 Get participation from everybody
35
Cause and Effect Analysis
Root Cause
How do we know when we have reached
ROOT CAUSE ?
Root Cause is the lowest cause in a chain of cause and
effect at which we have some capability to cause the
break
It’s within our capability to unilaterally control, or to influence,
changes to the cause

Products are failing for contamination
WHY? Base castings leak at mounting screw hole
WHY? Suppliers leak test may not detect porosity leak
WHY? Suppliers have different leak test processes
Can I cause
the break if
I stop here?
WHY? No standard process for supplier leak test
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Cause and Effect Analysis
Span of Control / Sphere of Influence
Before we begin, we must establish the context in which the
Cause-Effect will be used.
Span of Control - areas where we
have a high degree of control over
parts or functions, virtually complete
authority to change anything
SPHERE OF INFLUENCE
(Influence or persuasion only)
Sphere of Influence - areas where
we can influence things to varying
degrees but don’t have direct control.
SPAN OF CONTROL
(Full authority)
Outside Environment - where we
have neither control nor influence
OUTSIDE, UNCONTROLLED
ENVIRONMENT
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Cause and Effect Analysis
Points to Note for Fishbone Diagram




Treat the cause-and-effect diagram as a living
document
As new variables are discovered, update the
cause-and-effect diagram
After your experimental investigations, when
you have optimized the “X” factors, and
implemented control, update them to “C”.
Therefore, ideally, when the fishbone diagram
has more “C”s, the better we can control the
effect and improve its performance measure.
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