11MeasureStep02A(IntrotoSPC)（英文版）.pptx

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1、1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialY axis = Weight (lbs)10.5109.5Process = HoseFour Important Properties:(1) Centering(2) Spread(3)

2、 Shape(4) Stability Over Time1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential5 ft4 ft3 ft2 ft1 ft0 ft1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential5 ft4 ft3 ft2 ft1 ft0 ft1gVersion 4 3/016.1

3、Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential5 ft4 ft3 ft2 ft1 ft0 ftTimeWhat has changed?Centering? _Spread? _4.03.02.0Time1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential5 ft4 ft3 ft2 ft1 ft0 ftWhat has cha

4、nged?Centering? _Spread? _Time1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential5 ft4 ft3 ft2 ft1 ft0 ftWhat has changed?Centering? _Spread? _Time1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential

5、AvgSpreadAvgSpreadAvgSpreadAvgSpreadStable?Yes/No1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialDetective-Work for a Stable Process- Tracking the Y and Xs Simultaneously: Relationships- Active vs Passive Detective-Work- The Multi-Vari Study: Mec

6、hanics ExampleDetective-Work for an Unstable Process- Tracking the Y: Behavior Change = Learning Opportunity - Communicate SPC Effectively: Intuitive-Visual Approach- Get the Right “Meaning” From Your Data (Signal VS Noise)- Bubba: On the Straight and Narrow Path?- Inventory Management- The GoalDMAI

7、C = Doctors Detective-work- Hotel Detective-Work (Tempting to jump to conclusions/solutions?)Strategy #1Strategy #2What Data To Track Performance (Ys)? - Hospital Transactions (Where to shove the “Thermometers” to get data?)Analyze Phase = Diagnosis: Y= f(X,X,X,X,.,X)1gVersion 4 3/016.1Intro to SPC2

8、001, General Electric Company, USA. All rights reservedGE Confidential Bubba is known as “The straightest driver in Crick County”. One evening at Charlies Bar, he boasted, ”I drive so straight, even a quart of Moonshine wont throw me off target” Fed-up, Junior told him to “put his money where his mo

9、uth is” - a $100 bet. They selected Charlie, the bar owner, to be the impartial gum dropper.The Scene:1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialCharlie: The Impartial MediatorWarm, sticky, pre-chewed gumPre-Chewed CharliesBar and Grill1gVer

10、sion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialYou make the call:Did Bubba stay straightorloose $100?Junior says, “My gosh, it looks like you were swerving all over the place right from the beginning!”“Wheres my $100?”1gVersion 4 3/016.1Intro to SPC2

11、001, General Electric Company, USA. All rights reservedGE ConfidentialCONSIDER THIS .Why do the pieces of gum notland at the exact same location?Warm, sticky, pre-chewed gumPre-Chewed CharliesBar and Grill. even when Charlie is trying his best!1gVersion 4 3/016.1Intro to SPC2001, General Electric Co

12、mpany, USA. All rights reservedGE Confidential- Natural “Aim-to-Aim Variation” (due to Charlie)Sources of VariationTo develop common terminology, for now, lets simply call this “Aim-to-Aim Variation”1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidentia

13、lNow what do you think:Did Bubba stay straightorloose $100?Wouldnt it be helpful to have some way of separating the steering variation from the natural, inherent “Aim-to-Aim” Variation?1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialSources of Va

14、riation:- Natural Aim-to-Aim VariationWe can strategically use this natural, unavoidable variation (i.e., the spread width) as a tool for detecting shifts in the trucks centering.The Control Chart Approach1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confi

15、dentialFirst, select the spread that we will declare as the “Baseline Behavior”. Here, we will select “Natural Aim Variation”.Then, determine boundaries or limits that should contain virtually all (say 99.7%) of the “wiggling” (that is, if Charlies Aim continues to be the only Source of Variation pr

16、esent).Suppose that whenever any point lands outside these “control limits”, an alarm will sound.Like using a “Squelch” to separate Signals from the Noise:(Setting the squelch threshold level)(Detecting a signal being thats above and beyond the squelch threshold)1gVersion 4 3/016.1Intro to SPC2001,

17、General Electric Company, USA. All rights reservedGE Confidential- Aim Variation (only)Sources of Variation- Aim Variation- Variation Due to SteeringSources of VariationSo, if any shifts in the centering occur, we will know!1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All righ

18、ts reservedGE ConfidentialThats how control limits separate signals from noiseUCLLCLNo evidence of any changes in the true “centering” of the truck.All the “wiggling” of the data points was simply due to noise.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE

19、ConfidentialDetective-Work for a Stable Process- Tracking the Y and Xs Simultaneously: Relationships- Active vs Passive Detective-Work- The Multi-Vari Study: Mechanics ExampleDetective-Work for an Unstable Process- Tracking the Y: Behavior Change = Learning Opportunity - Communicate SPC Effectively:

20、 Intuitive-Visual Approach- Get the Right “Meaning” From Your Data (Signal VS Noise)- Bubba: On the Straight and Narrow Path?- Inventory Management- The GoalDMAIC = Doctors Detective-work- Hotel Detective-Work (Tempting to jump to conclusions/solutions?)Strategy #1Strategy #2What Data To Track Perfo

21、rmance (Ys)? - Hospital Transactions (Where to shove the “Thermometers” to get data?)Analyze Phase = Diagnosis: Y= f(X,X,X,X,.,X)1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential2030In-Process Inventory (X)10J F M A 19941995Award given April 1994:

22、 Manager pleased to see the in-process inventory drop to 15. Manager presents an award to Dept. 50 in honor of this achievement. Ceremony in the cafeteria: pizza and refreshments for all! “Everyone should be proud of what youve accomplished”.Derived from Understanding Variation: The Key To Managing

23、Chaos, Donald J. Wheeler, SPC Press. 1993.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential2030In-Process Inventory (X)10J F M A M J J 19941995Manager regrets giving award July 1994: Three consecutive months of inventory increases. Manager wishes

24、he could take back the award. “Recognition seems to have been backfired.” Instead of holding the gains, Dept.50 seems to have gotten complacent - allowing inventory to creep back to where it was previously. Manager decides: “This Mr. Nice Guy stuff doesnt work”Derived from Understanding Variation: T

25、he Key To Managing Chaos, Donald J. Wheeler, SPC Press. 1993.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential2030In-Process Inventory (X)10J F M A M J J A S O N D19941995 No more Mr. Nice Guy Nov. 1994: In-process inventory rises to a value of 26

26、! Manager decides to kick anatomy and take names. He calls everyone in and demands they do something to keep inventories down. Following this tantrum, everyone in Dept.50 treads lightly. Short of hiding material in the dark corners of the plant, they dont know what to do. So, they hold their breath

27、and hope inventories drop.Derived from Understanding Variation: The Key To Managing Chaos, Donald J. Wheeler, SPC Press. 1993.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential June 1995: Manager has seen reduced levels of inventory since the end o

28、f last year. “Things are looking-up!” (Although nothing had been done to change the system) His learning: “Tough management style gets results!”Manager concludes: “Tough management style gets results!”2030In-Process Inventory (X)10J F M A M J J A S O N D19941995J F M A M JDerived from Understanding

29、Variation: The Key To Managing Chaos, Donald J. Wheeler, SPC Press. 1993.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential2030In-Process Inventory (X)10J F M A M J J A S O N D19941995UCLJ F M M J J A S OLCL“But I always made sure my decisions/acti

30、ons were based on data!What could be wrong with that?” His decisions stemmed from interpreting the high and low points as signals. However, as the control chart below clearly reveals, NONE OF THESE INDIVIDUAL POINTS WERE SIGNALS! They all reflect the same underlying system - each should be interpret

31、ed alike.Derived from Understanding Variation: The Key To Managing Chaos, Donald J. Wheeler, SPC Press. 1993.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialManager concludes, “Tough management gets results!”J F M M J J A S O2030In-Process Invent

32、ory (X)10J F M A M J J A S O N D19941995Award givenManager regretsgiving awardNo more Mr. Nice GuyUCLLCL No matter how logical and persuasive the interpretation, and no matter how “right” youve been in the past - noise is still noise. Trying to interpret noise is nothing more than an exercise in wis

33、hful thinking. The result - pure fiction with no connection to reality.Derived from Understanding Variation: The Key To Managing Chaos, Donald J. Wheeler, SPC Press. 1993.1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential“Failure to use control cha

34、rts to analyze data is one of the best ways known to mankind to increase costs, waste effort, and lower morale.”- Dr. Donald J. Wheeler“Its not what we dont know that hurts.its what we know that aint so.”- Will RogersFalse lessons cost us - better to know how to use data wisely!Derived from Understa

35、nding Variation: The Key To Managing Chaos, Donald J. Wheeler, SPC Press. 1993.Manager concludes, “Tough management gets results!”J F M M J J A S O2030In-Process Inventory (X)10J F M A M J J A S O N D19941995Award givenManager regretsgiving awardNo more Mr. Nice GuyUCLLCL1gVersion 4 3/016.1Intro to

36、SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialVideo Segment(Optional)Watch how one managers decisions and actions are affected when he incorrectly interprets .NOISE (typical, inherent, minute-to-minute process variation behavior)SIGNAL(clearly different behavior - above a

37、nd beyond the usual noise)as if it were aDo you know any operators, co-workers, or managers who have managed processes this way?1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential“Teen Smoking Turns Upward”- USA Today, June,21,1994Percent By Year17.

38、017.518.018.519.019.519921993Year199217.3%199319.0%1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialYear%Smokers198418.8198519.6198618.7198718.6198818.1198918.9199019.2199118.2199217.3199319.093929190898887868584 212019181716YearIndividualsX=18.64

39、UCL=20.71LCL=16.573210Moving RangeR=0.7778UCL=2.541LCL=NoneI and MR Chart for %SmokersA Signal Above the Noise?1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialJust this. There is no evidence that the percentage of teenagers who smoke has increase

40、d. Neither is there any evidence that this percentage has decreased during the past 10 years. The only headline for these data that has any integrity is No change in teen use of tobacco. Anything else is just propaganda.So, what can we say about the percentage of teenagers who smoke daily?So how do

41、you avoid being persuaded by propaganda?By the way, did you read the article about how the Trade Deficit soared last April? Oh well, thats another story - or is it? The beginning is to realize that while all data contain noise, only some data contain signals. If you do not know how to separate the p

42、robable noise from the potential signals, you are susceptible to being misled by the noise in the data. Others may use data to mislead you - or you may even mislead yourself. Shewharts charts are the simplest way to separate signals from noise.1gVersion 4 3/016.1Intro to SPC2001, General Electric Co

43、mpany, USA. All rights reservedGE ConfidentialSelit Corp.s 4th Quarter Sales Report . . . Time NEast SWestNWestNCentralMAtlantic SCentral1995_Q4 95211968786708024621996_Q3 97611976887438074471996_Q4 11481337806702781359(Values In Columns = Sales In Thousands)Last QuarterCurrent QuarterSame QuarterLa

44、st YearA Case Study.Open minitab worksheet file “Sales (Quarterly Data).mtw”1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE Confidential“Kim, Mid-Atlantic sales were down 3.2% in the fourth quarter and down 2.6% from the previous year - a downward trend! Im

45、very disappointed in your performance. You were once my best sales representative. I had high expectations for you. Now, I can only hope that our first quarter results show some sign of life.” Kim felt her face get red. She knew she sold more units in 1996 than in 1995. “What does Halger know anyway

46、,” she thought to herself. “Hes just an empty suit.”802807781Selit Corp.s 4th Quarter Sales Report . . .Last QuarterCurrent QuarterSame QuarterLast YearMid-Atlantic1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialHagler continued: “Terry, Southwes

47、t sales were super. You showed an 11.7% increase in the fourth quarter and an 11.8% increase over the previous year” - An upward trend!Terry smiled. She wasnt sure how she did so well, but she sure wasnt going to change anything.119611971337Selit Corp.s 4th Quarter Sales Report . . .Last QuarterCurr

48、ent QuarterSame QuarterLast YearSouthWest1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialNoise = “Common Cause” VariationSignal = “Assignable Cause” Variation (or “Special Cause”) Brainstorming: List possible causes of both common and assignable

49、causesThe strategies for improving these two types of variation are very different !More about this later .Process: Driving to workMeasurement: Y = Travel timeExample:1gVersion 4 3/016.1Intro to SPC2001, General Electric Company, USA. All rights reservedGE ConfidentialNoise = “Common Cause” Variatio

50、nSignal = “Assignable Cause” Variation (or “Special Cause”) Brainstorming: List possible causes of both common and assignable causesThe strategies for improving these two types of variation are very different !More about this later .Process: Monthly Telephone BillMeasurement: Y = $Example:1gVersion