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“Have You Found

The ‘Root Cause’ Yet?”- A New Spin to Root Cause Analysis

Gary Jing, PhD, MBBNov 14, 2006

Root Cause Analysis - ASQGary Jing 11/14/06 Slide 2

The Tie Between the Speaker & the Topic

MS in Reliability & Applied StatisticsMS in Reliability & Applied Statistics

PhD in IEPhD in IE

Editorial Review Board of Editorial Review Board of Six Sigma Forum MagazineSix Sigma Forum Magazine

Founding MBB at Seagate TCO, the worldFounding MBB at Seagate TCO, the world’’s largest disc drive s largest disc drive

design center (1998 design center (1998 -- 2005)2005)

2 patents in disc drive modeling generated from his Sigma work2 patents in disc drive modeling generated from his Sigma work

Sr. Mgr., Global Lean Sigma / MBB, Entegris (2005 Sr. Mgr., Global Lean Sigma / MBB, Entegris (2005 -- present)present)


Personal Philosophy – Striving for Balance


Topics to be Covered

The Tie Between the Speaker & the Topic

The Mindset of Infinite Chain of Causation (New Spin 1)

The Role of Root Cause Analysis (RCA) in Six Sigma

Methodology

Popular RCA Tools Used in Six Sigma

– Differentiating & Prioritizing Causes (New Spin 2)

Summary


Cause-Effect Relationship

CAUSEEvents/conditions

that led tothe problem

A PROBLEM WHICHHAS OCCURED

EFFECTSymptoms that

provide evidenceof the problem

ACTION

CORRECTIVE

Eliminates the

CAUSE

of a problem

ADAP

TIVE

Lim

its th

eEF

FECT

of a

prob

lem

or d

evia

tion

Dave Wessel, “An Ounce of Prevention”, Quality Progress, Dec, 1998


Cause-Effect Principle – Chain of Causation

The same thing is both a cause and an effect at the same time.

Causes and effects are part of an infinite continuum of causes.

Injury caused by Fall

Fall caused by Wet Surface

Wet Surface caused by Leaky ValveLeaky Valve caused by Seal FailureSeal failure caused by Poor Maintenance

EFFECTS CAUSES

Reference: Apollo Root Cause Analysis, Dean L. Gano5 Why’s...


The Concept of Infinite Chain of Causation

Widely seen in philosophical level of discussion. e.g., Hegel’s philosophy.

“An important feature of causality is the continuity of the cause-effect connection. The chain of causal connections has neither beginning nor end. It is never broken... And no one can say where this chain began or where it ends. It is as infinite as the universe itself. There can be neither any first (that is to say, causeless) cause nor any final (i.e., inconsequential) effect. If we were to admit the existence of a first cause we should break the law of the conservation of matter and motion. And any attempt to find an ‘absolutely first’ or ‘absolutely final’ cause is a futile occupation, which psychologically assumes a belief in miracles.” - A. Spirkin, Dialectical Materialism

Applied by Dean L. Gano in Apollo Root Cause Analysis - A New Way Of Thinking, He warned that “because this book challenges conventional wisdom, it may not validate your existing belief system". -


Root Cause Analysis (RCA)

Challenge!!!: With infinite layers of Cause and Effect, how do we know where to stop and conclude we have reached “Root Cause”?

– Case study 1: Jefferson Memorial

“Have you found ‘the root cause’?”– The term “root cause” is somewhat misleading– A so-called “root cause” is subjectively chosen to serve as

the “root cause”

RCA Theme– Continuously migrate the focus to upstream causes– Keep asking “why” like a 2-year old


So, Where to Stop?- To conclude we have reached “Root Cause”?

Usually the lowest cause in a chain at which we have some capability to cause the break is chosen as the root cause.

The lowest level at which it is within our capability to unilaterally control, or to influence, changes to the cause


Three Important Principles . .

Where to stop? Where to stop? -- The trick is The trick is not to find the not to find the ““truetrue”” root causeroot cause per se. per se.

-- The trick is where to stop and treat what you have as The trick is where to stop and treat what you have as the root cause. That wisdom is what differentiates an the root cause. That wisdom is what differentiates an adult from a 2adult from a 2--year old; an expert from a novice. year old; an expert from a novice.

– The bottom-line is High ROI – low cost with high return.

-- Three tips:Three tips:– Leverage Point Thinking– Pareto Principle– Span of Control / Sphere of Influence


Leverage Point Thinking & Pareto

How Do You Turn the Ship?Knowing the leverage points is critical for determining priorities and strategies for improvement

Vital Few

Trivial Many

Pareto Principle 80% of the problems are caused by only about 20% of the contributing factors.

Case study 2: The “Snow Map”


Span of Control / Sphere of Influence

SPHERE OF INFLUENCE(Influence or persuasion only)

SPAN OF CONTROL(Full authority)

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 - areas where we can influence things to varying degrees but don’t have direct control.

Outside Environment - where we have neither control nor influence

OUTSIDE, UNCONTROLLEDENVIRONMENT


The Role of RCA in Six Sigma Methodology- DMAIC Process (Roadmap)

Define Define the problem; Establish project charter (goals, scope, team & timeline)

Measure Identify customer requirements / Critical To Quality (CTQ’s)Translate into measurable Key Process Output Variables (KPOV’s) Verify measurement system Establish present capabilityIdentify any factors / Key Process Input Variables (KPIV’s) that may

potentially affect the outputs (KPOV’s) through process mapping Establish high potential suspects (hypotheses) through cause-effect

analysis (subjective analysis using experience & expertise)

Analyze Validate the suspects / hypotheses using existing data through statistical testing (objective analysis)

Reduce list of high potential KPIV’s to vital fewImprove Generate improvement ideas using soft tools (subjective)

Use DOE to generate new data when no existing data available and to optimize & validate outputs (objective)

Control Put in place permanent controls


Five Types of Cause-Effect Analyses

1. Is / Is not Comparative Analysis2. 5 - Whys3. Fishbone Diagram (Cause-effect Diagram) - Traditional

approach to brainstorming and diagramming Cause-Effect relationships. Good tool when there is one primary effectbeing analyzed.

4. Cause & Effect Matrix - Used to relate and prioritize X’s to customer CTQ’s through numerical ranking. Good tool when there is more than one primary effect being analyzed.

5. Root Cause Tree - A problem analysis diagram that begins with undesirable effects and works back to root causes and core problems.


Cause-Effect Analysis

I keep six honest serving men,

They taught me all I knew,

Their names are What and Why and How

and Where and When and Who

Rudyard Kipling


Is / Is Not Comparative Analysis

How many objects with the defect? How many defects per object? Size of defect? Trend?

Size

When was the defect first observed? When since then? When in the product life cycle?

When

Geographically? Physically on the part?

Where

What similar objects could have the defect but do not? What other defects could be observed but are not?

What is the specific object has the defect? What is the specific defect?

What

Differences and Changes

Is NotIs

Statement:Problem

Where, when and what size could the defect have been but it was not?


Fish Bone Diagram

- Focusing on single effect with simplecause-effect relationships


“Fishbone” Cause-Effect DiagramAdvantages

Helps organize and relate factorsProvides a structure for brainstormingInvolves everyone

DrawbacksMight become very complexRequires patienceDoes not rank the causes in an if- thenmanner

MethodsMaterials

Machinery Manpower

C/N/X

C

C

C

N N

NNN

C

C

Problem/Desired

Improvement

C = Control FactorN = Noise FactorX = Factor for DOE (chosen later)

Opportunity:H: HighM: MediumL: Low

Controllability:C: Within controlI: Have influenceN: No influence

New spin 2: Categorizing / labeling Causes:


Use Cause and Effect Diagram to Single Out Variation Sources within the “5M’s + E”

Use Cause and Effect Diagram to Single Out Variation Sources within the “5M’s + E”

Man

MethodsMachine

Materials Measurement

Five Key Sources of Variation

Environment+

Product: The 5M’s


You can merge the cause and effect with the affinity diagram by placing your Post-Its directly onto the fish. This helps reduce the number of headings generated.

You can merge the cause and effect with the affinity diagram by placing your Post-Its directly onto the fish. This helps reduce the number of headings generated.

People

ProceduresPolicies

Place Measurement

Five Key Sources of Variation

Environment+

Transactional or Process: 4P’s + M&E


Fishbone Example #2

HighNumber o finv en to ryad ju stments

Env iro nmen t

Retu rn s

Receip ts

P ro cedu res

Data En try

C y c le C o un ts

w rong counts

N o D ata av a ilable

B ad T y ping

A ccuracy of counts

Lack of tra ining

N ot be ing done

Line shut dow n

ov er sta ted inv entory

G oods issue not done

incorrectquantity

w rong partsrece iv ed

excessinv entory

w ork orderv ariance

N o I nv entory bylocation

Lack of S pace

em pl o ye esTemp

o rd e rswo rk

Ope n

Requ is iti o ns

Inventory AdjustmentsAGB project: New spin 2: Differentiate causes.


Weaknesses of the Fishbone

Although the “fishbone” cause-effect diagram has been very popular over the years, it has some inherent weaknesses:

_______________________________________

_______________________________________

_______________________________________

_______________________________________


Cause and Effect Matrix

- To evaluate the impact of a group of causes on a group of effects



Rating of Importance to

Customer1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Req

uire

men

t

Total

Process Step Process Input

1 02 03 04 05 06 07 08 09 010 011 012 013 014 015 016 017 018 019 020 0

0

Total 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lower Spec

TargetUpper Spec


C&E Matrix.xls


C-E Matrix: Example

10 6 9 8

1 2 3 4 5 6

Effic

ienc

y

Com

mon

ality

Yiel

d (a

ccur

acy)

Cha

nge

Impl

emen

tatio

n

1 Customer Input 8 6 8 8 252 11.36%2 Equipment Specs 8 5 10 8 264 11.90%3 Bill of Materials 7 5 10 5 230 10.37%4 # of Revisions 8 6 10 8 270 12.17%

5Label Documentation 8 2 8 9 236 10.64%

6 CC Drawings 5 3 2 2 102 4.60%7 Pre-CCP Metting 5 5 2 2 114 5.14%8 Ownership 8 10 8 8 276 12.44%9 Approval Cycles 8 8 5 8 237 10.69%

10 AMK Delays 8 8 5 8 237 10.69%

2218

Rating of Importance to Customer

TOTAL %

PROCESS INPUTS Sometime it’s

used to rank

Fishbone inputs.

Customer ECO Throughput ReductionCustomer ECO Throughput Reduction


Cause-Effect Matrix Analysis Example

0.1 0.5 1 3 5 1 -2 1 -2

Material

# of adjustm

ent entry / Total

Added quantity

/ total

Substracted

quantity / total

Added $ / Total

Substracted $ / Total Overall

Added quantity/ consum

ption

Substracted

quantity/ consum

ption

Added $/

consumption

Substracted $ / consum

ption

Rank without Consum

ption Info

Rank by Substracted $

Overall Rank

830R25 0.001 0.000 0.001 0.000 0.027 0.138 -2.840 -2.840 11 4 1225 0.001 0.000 0.036 0.000 0.013 0.102 0.028 -2.807 0.028 -2.807 18 17 2

7500-0585-03 0.007 0.020 0.037 0.003 0.004 0.076 0.358 -0.317 0.357 -0.316 28 51 301-001638 0.004 0.000 0.003 0.042 0.184 1.050 0.011 -0.036 0.011 -0.036 1 1 401-006154 0.005 0.004 0.010 0.008 0.014 0.108 0.183 -0.244 0.157 -0.209 15 15 5

4002-5973-02 0.002 0.002 0.006 0.004 0.012 0.081 0.102 -0.202 0.102 -0.202 24 20 601-004488 0.003 0.001 0.005 0.009 0.061 0.337 0.027 -0.134 0.027 -0.134 2 2 7

8100-0100-01 0.012 0.009 0.000 0.067 0.000 0.206 0.564 0.564 7 403 8200 0.003 0.009 0.034 0.005 0.013 0.117 0.071 -0.135 0.071 -0.135 13 18 9

7500-0585-07 0.003 0.024 0.017 0.008 0.004 0.071 0.258 -0.092 0.258 -0.092 30 52 101032-047 0.018 0.052 0.000 0.014 0.000 0.069 0.570 0.569 32 403 11PKG-782 0.017 0.131 0.000 0.009 0.000 0.096 0.530 0.530 20 403 12

01-009871 0.002 0.002 0.005 0.018 0.030 0.212 0.072 -0.083 0.071 -0.084 6 3 1301-009644-17C02 0.001 0.000 0.001 0.006 0.017 0.103 0.047 -0.107 0.046 -0.103 17 11 14

9700-7036-01 0.003 0.004 0.002 0.049 0.018 0.241 0.141 -0.037 0.141 -0.037 4 8 1501-001651 0.003 0.003 0.005 0.015 0.020 0.152 0.073 -0.070 0.073 -0.070 9 7 16

160 0.001 0.000 0.001 0.000 0.016 0.079 -0.095 -0.094 25 13 1701-018514 0.016 0.034 0.000 0.073 0.000 0.238 0.203 0.203 5 403 1801-021524 0.001 0.001 0.003 0.008 0.016 0.109 0.062 -0.069 0.047 -0.071 14 12 1901-009897 0.003 0.002 0.008 0.003 0.011 0.076 0.029 -0.076 0.029 -0.077 27 21 2001-021554 0.001 0.000 0.002 0.001 0.012 0.069 0.013 -0.073 0.014 -0.087 31 19 21

Inpu

t Var

iabl

es -

Mat

eria

ls

Output Variables that Reflect the Impact of Adjustment

RankWeight

AGB project: Inventory Accuracy

Sometime the ranking can be objective, data driven.


Root Cause Tree (RCT)

- For more complicated cause - effect relationships (causes may be dependent on each other)


Example of RCT

AGB project: Potting Leaks


Distinguishing Undesirable Effects From Neutrals

Two “Rules of Thumb”1. What bearing does the effect have on the system goal?2. Does the effect pass the “So What” test?

UDE’s are negative on their own meritNo further explanation why is neededEffects are negative at face value

“We lost money last quarter”*Undesirable Effects


Rules, Guidelines

Clarity: Someone stating a cause-effect relationship must take care to ensure that others will:

– Understand the individual words

– Comprehend the meaning of the idea

– See a clear connection between cause and effect

Purpose: To help us construct our own logical relationships and to evaluate the logic of others


Rules, GuidelinesCausality Existence– Tests the connections– One basic criterion: Does the proposed cause really produce the

observed effect?– The Cause-Effect relationship must be direct and unavoidable– If not clear - keep looking, you missed something

I can’t buy a new car

I can’t buy a new car

I have lessdisposable income

Taxes areraised

Taxes areraised

?


Rules, Guidelines

Cause Insufficiency– Be sure you have identified and included all of the major contributing

causes– To be contributing, causes must depend on one another– Two questions:

• Is the cause alone enough to deliver the effect?• If I take away one of the causes, will I still have the effect?

I leave mybook outdoors

My book gets wet

I leave mybook outdoors

My book gets wet

It rainstoday

“AND”


Rules, Guidelines

Additional Cause– Consider all possible independent causes– A cause may consist of several independent causes, any of

which would have produced the effect– Each independent cause would increase the magnitude of

the observed effect

Bills areignored

Accounts receivableare too high

Paymentsare late

Bills arepartially paid


Rules, Guidelines

Circular reasoningThe effect is the rationale for the existence of the cause– More common in conversation than on graphs– Example:

• The fisherman brought home several large fish• WHY? - The fishing was good• HOW DO YOU KNOW? - He brought home several large fish, didn’t he?


Example RCTCustomer suffered a corrosion

problem, meantime they tested a surge of sulfate with our product. They suspect it’s the primary contributor and demand for the root cause and control.

A. Understand the meaning and “reliability”

of customer data

The readingsare the

calculated Sulfate

concentration of product /

resin?(surface

only?) or the sulfate

concentration of test

coupon / water? L,N

Correlation doesn’t mean causation. Is Sulfate really the

primary contributor?(Otherwise it may not help the problem.) – Need to work with

customer and their data. M,I

What’s the repeatability

and reproducibilityof customer

data. L,N

What’s the Correlation

between our data and their data. L,N

B. Internal measurement of

Sulfur related anion

C. SRA originated from original material

D. SRA introduced during manufacturing

process

B1. Where do we measure

SRA, R&R. H,C

B2. Resin test. M,IB3. Test

prime product?

H,C

B4. Test cleaned product?

H,C

B5. Test / monitor cleaning

solution? H,C

B6. Air quality. M,C

E. SRA introduced after manufacturing

C1. Lot to lot

variation. H,N

SRA transform during

manufacturing. M,I

During molding.

L,I

During Cleaning.

L,CExposing to air. M,N

Cross contamination

when lines shift products.

L,I

Resin absorb SRA from air. M,C

Outside cleanroom

Inside cleanroom

Parts absorb SRA from air inside cleanroom. M,C

Bag contamination.

L,C

E1. Product absorb SRA

overtime.H,I

Contamination through leaking

bag. L,I

SRA transform overtime.

M,N

Product release

SRA overtime.

L,I

Opportunity:H: HighM: MediumL: Low

Controllability:C: Within controlI: Have influenceN: No influence

Color code:• Being studied• Should investigate

Cleaning removes /

absorb SRA. M,C

B7. Sample size. M,I

(SRA – Sulfur related anion)


Summary

New Spin 1: The Mindset of Infinite Chain of Causation

The Role of Root Cause Analysis (RCA) in Six Sigma

Methodology

Popular RCA Tools Used in Six Sigma – Is / Is not analysis– Fishbone Diagrams (Cause-effect Diagram)– C&E Matrix– Root Cause Tree

New Spin 2: Differentiating & prioritizing causes

Documents

“Have You Found The ‘Root Cause’ Yet?”mnasq.org/files/summaries/rootcauseanalysis.pdfpurify protect transport “Have You Found The ‘Root Cause’ Yet?” - A New Spin to