The Tie Between the Speaker & the Topic

Transcription

1 purify protect Have You Found The Root Cause Yet? - A New Spin to Root Cause Analysis transport Gary Jing, PhD, MBB Nov 14, 26 The Tie Between the Speaker & the Topic MS in Reliability & Applied Statistics PhD in IE Editorial Review Board of Six Sigma Forum Magazine Founding MBB at Seagate TCO, the world s s largest disc drive design center ( ) 2 patents in disc drive modeling generated from his Sigma work Sr. Mgr., Global Lean Sigma / MBB, Entegris (25 - present) Gary Jing 11/14/6 Slide 2

2 Personal Philosophy Striving for Balance Gary Jing 11/14/6 Slide 3 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 Gary Jing 11/14/6 Slide 4

3 Cause-Effect Relationship A PROBLEM WHICH HAS OCCURED CAUSE Events/conditions that led to the problem Eliminates the CAUSE of a problem CORRECTIVE ACTION EFFECT Symptoms that provide evidence of the problem ADAPTIVE Limits the EFFECT of a problem or deviation Dave Wessel, An Ounce of Prevention, Quality Progress, Dec, 1998 Gary Jing 11/14/6 Slide 5 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. 5 Why s EFFECTS CAUSES Injury caused by Fall Fall caused by Wet Surface Wet Surface caused by Leaky Valve Leaky Valve caused by Seal Failure... Seal failure caused by Poor Maintenance Reference: Apollo Root Cause Analysis, Dean L. Gano Gary Jing 11/14/6 Slide 6

4 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". - Gary Jing 11/14/6 Slide 7 Root Cause Analysis (RCA) 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 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 Gary Jing 11/14/6 Slide 8

5 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 Gary Jing 11/14/6 Slide 9 Three Important Principles.. Where to stop? - The trick is not to find the true root cause per se. - The trick is where to stop and treat what you have as the root cause. That wisdom is what differentiates an adult from a 2-year 2 old; an expert from a novice. The bottom-line is High ROI low cost with high return. - Three tips: Leverage Point Thinking Pareto Principle Span of Control / Sphere of Influence Gary Jing 11/14/6 Slide 1

6 Leverage Point Thinking & Pareto How Do You Turn the Ship? Knowing the leverage points is critical for determining priorities and strategies for improvement Case study 2: The Snow Map Vital Few Trivial Many Pareto Principle 8% of the problems are caused by only about 2% of the contributing factors. Gary Jing 11/14/6 Slide 11 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 - areas where we can influence things to varying degrees but don t have direct control. Outside Environment - where we have neither control nor influence SPHERE OF INFLUENCE (Influence or persuasion only) SPAN OF CONTROL (Full authority) OUTSIDE, UNCONTROLLED ENVIRONMENT Gary Jing 11/14/6 Slide 12

7 The Role of RCA in Six Sigma Methodology - DMAIC Process (Roadmap) Define Define the problem; Measure Analyze Improve Control Establish project charter (goals, scope, team & timeline) Identify customer requirements / Critical To Quality (CTQ s) Translate into measurable Key Process Output Variables (KPOV s) Verify measurement system Establish present capability Identify 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) Validate the suspects / hypotheses using existing data through statistical testing (objective analysis) Reduce list of high potential KPIV s to vital few Generate improvement ideas using soft tools (subjective) Use DOE to generate new data when no existing data available and to optimize & validate outputs (objective) Put in place permanent controls Gary Jing 11/14/6 Slide 13 Five Types of Cause-Effect Analyses 1. Is / Is not Comparative Analysis Whys 3. Fishbone Diagram (Cause-effect Diagram) - Traditional approach to brainstorming and diagramming Cause-Effect relationships. Good tool when there is one primary effect being 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. Gary Jing 11/14/6 Slide 14

8 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 Gary Jing 11/14/6 Slide 15 Is / Is Not Comparative Analysis Problem What Where When Size Statement: Is What is the specific object has the defect? What is the specific defect? Geographically? Physically on the part? When was the defect first observed? When since then? When in the product life cycle? How many objects with the defect? How many defects per object? Size of defect? Trend? Is Not What similar objects could have the defect but do not? What other defects could be observed but are not? Where, when and what size could the defect have been but it was not? Differences and Changes Gary Jing 11/14/6 Slide 16

9 Fish Bone Diagram - Focusing on single effect with simple cause-effect relationships Gary Jing 11/14/6 Slide 17 Fishbone Cause-Effect Diagram Advantages Helps organize and relate factors Provides a structure for brainstorming Involves everyone Drawbacks Might become very complex Requires patience Does not rank the causes in an if- then manner Materials C Methods C C/N/X C = Control Factor N = Noise Factor X = Factor for DOE (chosen later) N N C N C N N C Problem/ Desired Improvement New spin 2: Categorizing / labeling Causes: Machinery Manpower Opportunity: H: High M: Medium L: Low Controllability: C: Within control I: Have influence N: No influence Gary Jing 11/14/6 Slide 18

10 Product: The 5M s Man Machine Materials Five Key Sources of Variation Methods + Environment Measurement Use Use Cause and and Effect Diagram to to Single Out Out Variation Sources within the the 5M s + E E Gary Jing 11/14/6 Slide 19 Transactional or Process: 4P s + M&E People Policies Place Five Key Sources of Variation Procedures + Environment Measurement You You can can merge the the cause and and effect with with the the affinity diagram by by placing your your Post-Its directly onto onto the the fish. fish. This This helps reduce the the number of of headings generated. Gary Jing 11/14/6 Slide 2

11 Fishbone Example #2 AGB project: Inventory Adjustments New spin 2: Procedures Cycle Counts Differentiate causes. Returns work order variance G oods issue not done ov er stated inv entory Bad Ty ping No Data av ailable Requisitions excess inv entory No Inventory by location Line shut dow n incorrect quantity Ope n Te mp work em ploye es orde rs w rong counts A ccuracy of counts Lack of training High Number of in v en to ry adjustments Lack of S pace wrong parts receiv ed N ot being done Environment Receipts Data En try Gary Jing 11/14/6 Slide 21 Weaknesses of the Fishbone Although the fishbone cause-effect diagram has been very popular over the years, it has some inherent weaknesses: Gary Jing 11/14/6 Slide 22

12 Cause and Effect Matrix - To evaluate the impact of a group of causes on a group of effects Gary Jing 11/14/6 Slide 23 Cause and Effect Matrix Cause and Effect Matrix Rating of Importance to Customer Total Process Step Process Input C&E Matrix.xls Total Lower Spec Target Upper Spec Gary Jing 11/14/6 Slide 24

13 C-E Matrix: Example Customer ECO ECO Throughput Reduction Rating of Importance to Customer PROCESS INPUTS Efficiency Commonality Yield (accuracy) Change Implementation TOTAL % Sometime it s used to rank Fishbone inputs. 1 Customer Input % 2 Equipment Specs % 3 Bill of Materials % 4 # of Revisions % 5 Label Documentation % 6 CC Drawings % 7 Pre-CCP Metting % 8 Ownership % 9 Approval Cycles % 1 AMK Delays % 2218 Gary Jing 11/14/6 Slide 25 Cause-Effect Matrix Analysis Example Output Variables that Reflect the Impact of Adjustment AGB project: Inventory Accuracy Input Variables - Materials Weight Material Substrac ted # of adjustm ent entry / Total Added quantity / total Substra cted quantity / total Added $ / Total Substra cted $ / Total Overall Added quantity/ consum ption quantity/ consum ption Added $/ consum ption Substra cted $ / consum ption Gary Jing 11/14/6 Slide 26 Rank Rank without Consum Rank by ption Info Substra cted $ Overall Rank 83R PKG C Sometime the ranking can be objective, data driven.

14 Root Cause Tree (RCT) - For more complicated cause - effect relationships (causes may be dependent on each other) Gary Jing 11/14/6 Slide 27 Example of RCT AGB project: Potting Leaks Gary Jing 11/14/6 Slide 28

15 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 merit No further explanation why is needed Effects are negative at face value We lost money last quarter *Undesirable Effects Gary Jing 11/14/6 Slide 29 Rules, Guidelines Purpose: To help us construct our own logical relationships and to evaluate the logic of others 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 Gary Jing 11/14/6 Slide 3

16 Rules, Guidelines Causality 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 less disposable income Taxes are raised Taxes are raised Gary Jing 11/14/6 Slide 31 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? My book gets wet My book gets wet AND I leave my book outdoors I leave my book outdoors It rains today Gary Jing 11/14/6 Slide 32

17 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 Accounts receivable are too high Payments are late Bills are ignored Bills are partially paid Gary Jing 11/14/6 Slide 33 Rules, Guidelines Circular reasoning The 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? Gary Jing 11/14/6 Slide 34

18 Example RCT (SRA Sulfur related anion) Customer 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. Opportunity: H: High M: Medium L: Low Controllability: C: Within control I: Have influence N: No influence Color code: Being studied Should investigate A. Understand the meaning and reliability of customer data B. Internal measurement of Sulfur related anion C. SRA originated from original material D. SRA introduced during manufacturing process E. SRA introduced after manufacturing What s the repeatability and reproducibility of customer data. L,N What s the Correlation between our data and their data. L,N The readings are 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 B1. Where do we measure SRA, R&R. H,C B3. Test prime product? H,C B4. Test cleaned product? H,C B6. Air quality. M,C B5. Test / monitor cleaning solution? H,C C1. Lot to lot variation. H,N B7. Sample size. M,I B2. Resin test. M,I During Cleaning. L,C Outside cleanroom Inside cleanroom SRA transform during manufacturing. M,I Exposing to air. M,N During molding. L,I Resin absorb SRA from air. M,C Cross contamination when lines shift products. L,I Bag contamination. L,C Contamination through leaking bag. L,I Parts absorb SRA from air inside cleanroom. M,C Cleaning removes / absorb SRA. M,C E1. Product absorb SRA overtime. H,I SRA transform overtime. M,N Product release SRA overtime. L,I Gary Jing 11/14/6 Slide 35 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 Gary Jing 11/14/6 Slide 36