Cause and Effect Analysis
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Six SigmaGreen Belt
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Cause and Effect AnalysisCause and Effect Analysis
Sigma Quality Management
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Six SigmaGreen BeltCause & Effect in Business ProcessesCause & Effect in Business Processes
Input (X)
Methods Materials Machines Personnel Environment
Y = F(X)
Process (X) Output (Y)
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Six SigmaGreen BeltRoadmap for Analyzing CausesRoadmap for Analyzing Causes
Examine the Process, Address
Assignable/ Special Causes of Variation Check Process
and Make Quick and Easy
Improvements
Stratify Data to Identify Specific
ProblemsDevelop Cause and Effect Diagrams for
the Specific Problems
Verify Root Causes
To Improve & Execute Steps
From Measure Step
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Six SigmaGreen BeltSimple Cause & EffectSimple Cause & Effect
Examining the Process� Common Sense� Process Documentation� Actual vs. Documented Process� Training� Data Analysis
Quick and Easy Improvements� Eliminate redundancies� Clarify unclear steps� Re-order steps� Eliminate unnecessary steps� Decrease the amount of transportation or delays
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Six SigmaGreen BeltSimple Cause & EffectSimple Cause & Effect
Stratifying the Data – Pareto
Involving the Right People
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Six SigmaGreen BeltCause & Effect (Ishikawa) DiagramCause & Effect (Ishikawa) Diagram
EFFECT
PERSON MACHINE
MATERIALMETHOD
ENVIRONMENT
Major Bone
Medium Bone
Small Bone
Head
Backbone
Kaoru Ishikawa – Our Hero!
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Six SigmaGreen BeltStepsSteps
1. State the problem as the Effect. A good "Effect" statement:� states what is wrong, not why it is wrong,� focuses on the gap between what is and what should be, and� is measurable and specific.
2. Identify possible causes of the Effect. Brainstorm a list of causes based on knowledge of the production process.� "Ask Why Five Times"� Avoid:
• Solutions• "Lack of" Statements• "Fuzzy" causes
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Six SigmaGreen BeltSteps (continued)Steps (continued)
3. Define the major categories to be used on the Cause and Effect diagram. “Default" categories - Person, Machine, Material, Method, Information, and Environment.
4. Draw the diagram. Refine the causes where necessary and continue
asking:� What causes this?� Why does this condition exist?
5. Walk through the logic in both directions: a) proceed from the effect to the causes, andb) proceed from the causes to the effect.
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Six SigmaGreen BeltVariation/Problem Analysis TypeVariation/Problem Analysis Type
W eld Splits inTubing
Overexpanding
TubingDefects
People
Equipm entdefective
Not followingprocedures
Not trained
Procedurenot available
Notm aintainedProcedure
not correct
Poor weldseam s
Supplier notqualified
Tubingdegraded
PoorAttitude
No peopleto m aintain
No people tom onitor splits
No budget
Sales down
Equipm entchanged
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Six SigmaGreen BeltProduction Process - FocusedProduction Process - Focused
Departure from GI/GU
Daily Schedule
Patient Arrival
Registration Patient Prep
Procedure
Recovery
Room Cleanup
Arrives Late
Not Aware of Schedule
Traffic
Can't Find Lab
Paperwork Delays
Patient Queue
Insurance Verification
Delays
Supplies Unavailable
Patient Difficulties
Crew Distracted
Patient Uncooperative
Unusual Findings
Physician Process
Emergency/Code
Sedation
Talkative Patient
Supplies Unavailable
Crew Distracted
Emergency/Code
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Six SigmaGreen BeltOthersOthers
Comparative Cause & Effect
Planning Cause & Effect
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Six SigmaGreen BeltCause & Effect VerificationCause & Effect Verification
Effect
Person Machine
Material Method
Environment
CAUSE AND EFFECT DIAGRAM
Root Cause G
Root Cause A
A B C D E G Spec
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Six SigmaGreen BeltVerification Methods - Absence/PresenceVerification Methods - Absence/Presence
Cycle Time/Unit
010
2030
40
1 4 7 10 13 16 19 22 25 28 31 34 37 40
Units
Tim
e(da
ys)
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Six SigmaGreen BeltVerification Methods - Absence/PresenceVerification Methods - Absence/Presence
100
75
50
25
0
Causes of Defects127125
100
75
50
25
0
% o
f def
ects
Freq
uenc
y
A B
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Six SigmaGreen Belt
Value
Value
Verification Methods - Absence/PresenceVerification Methods - Absence/Presence
Frequency
Performance With Factor Absent
Frequency
Performance With Factor Present
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Six SigmaGreen BeltVerification Methods – Variable LevelVerification Methods – Variable Level
Driving Speed(MPH)
Gas Mileage (MPG)
20
26
35 75
Automobile Gas Mileage
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Six SigmaGreen BeltVerification MatrixVerification Matrix
Problem Potential Causes Tests/Verifications
Inner Sleeve Cracking
Batch of Sleeves with poor material properties
Mixing of Lubricating Oils
Case Hardened vs. Through Hardened steel
Replacement interval too long
Contamination in Lube Oil
Excessive Stress on Sleeves
Inadequate Interference Fit - Combination Sleeve too Large and Axle too Small (specs)
Axle Upset due to Wheel Pulling Stresses
Mat'l Test Oil Sample Weibull An'l. Fracture An'l. Dimensioning
Mat'ls Tested OK
Not a Problem for Journal Box Lubr.
Other Roads use Case, ours uses Through
B -10 Life is 38 Mo., we repl. on 60 Mo.
High Sand levels found in J.B. Oil
Fracture Rpt. indicates High Stress on Axle
1% Chance of too small inter. fit (30 data)
Axles meas'd. no taper or out of round