Six Sigma Simplicity

Explain Six Sigma Simply(Football story from SSDSI)

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Six Sigma Simplicity

Reduce Variation, Make MoneyWe teach the concept of ‘Six Sigma’ with a story that helps our students understand the concept. A football coach is evaluating five kickers as field goal kickers for an upcoming game. He has a GPS solution that tells him exactly where the ball crosses the field goal. He gives each of his kickers 100 chances to kick the ball through the goal posts (spec limits) from the center of the field at 35 yards back.

His first four kickers take their turns. Each kicker kicks all 100 balls between the uprights, but all four kickers were "all over the place", meaning that they never consistently crossed the goal post at the same point. The fifth kicker also kicks all 100 through the uprights but he consistently "splits" the uprights.

We then ask the class, "Who are you going to choose when it comes time to kick a field goal during the game?". Most will choose the fifth kicker. Why? ... because he is more consistent. The fifth kicker will be more predictable because he has learned to have better control over the critical inputs when kicking the ball. If you were to film all 100 kicks that the fifth kicker made, you would see little variation in his kicking method which leads to little variation in his output, which is the ball "splitting the uprights“ down the middle.

Six Sigma Simplicity

Sigma Illustrated

• Sigma is used to describe the “spread” of a distribution relative to it’s center (mean)

• What changed in the graphs below?

Six Sigma Simplicity

How Does Sigma Help?

• Most things in nature to have a common shape relative to variation

• That common shape is referred to as a normal distribution

• Using that normal distribution allows us to determine a probability of occurrence based on some middle value and the amount of variation in the group

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Normal Distribution

• The area under sections of the curve can be used to estimate the cumulative probability of a certain “event” occurring

43210-1-2-3-4

40%

30%

20%

10%

0%

95%

Prob

abili

ty o

f sam

ple

valu

e

Number of (sigma) standard deviations from the mean

99.73%

68%Cumulative probability of obtaining a value between two values

Cumulative probability of obtaining a value between two values

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Lower Spec Upper Spec

sss ss s sss ss s

6 Sigma Capability = 12 Std Deviations (Total)Recall: this is 3 Sigma Capability

Six Sigma capability is where the distance between the mean and the nearest specification limit equals 6 standard deviation units

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Visualizing – Which is Better? Why?

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0.4

0.3

0.2

0.1

0.0

Lower Spec. Limit

Upper Spec. Limit

3 Sigma

86420-2-4-6-8

0.4

0.3

0.2

0.1

0.0

Lower Spec Limit

Upper Spec. Limit

6 Sigma

Six Sigma Simplicity

Dissecting Capability: Sources of Variability

LSL USL

Defectsresulting in

additional cost

Process Distribution

EnvironmentProcess/ Assembly Variation

Material / Component

Variation

Measurement Variation

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2 308,5373 66,8074 6,2105 2336 3.4

s PPM

Defects per Million

Opportunity (DPMO)

2 69.1%

3 93.32%

4 99.379%

5 99.9767%

6 99.99966%

s % Non-Defective

What is the Significance of Sigma?

Six Sigma Simplicity

99% Good (3.8 sigma)

• 50 newborn babies dropped at birth by doctors each day

• Toxic drinking water for 15 minutes each day

• 5,000 incorrect surgical operations per week

• 204,000 wrong drug prescriptions each year

• Two short or long landings at major U.S. airports each day

99.99966% Great (6 sigma)

• 6 newborn babies dropped in a year

• Unsafe water for one minute every seven months

• 1.7 incorrect surgical operations per week

• 68 wrong prescriptions each year• Two short or long landings at

major U.S. airports in 10 years

Why 99% Isn’t Always Enough

Six Sigma Simplicity

7

Sigma Level

1,000,000

100,000

10,000

1,000

100

10

1

PPM

Restaurant BillsPayroll Processing

Prescription Writing

Baggage Handling

AirlineSafety Rate

3 4 5 621

Best in Class

Tax Advice

What Does 6 Sigma Mean In Your Daily Life?

Six Sigma Simplicity

More Examples

99% Good (3.8σ)

• No electricity for almost seven hours per month

• 1 misspelled word per 30 pages in a book

• 11.8 million shares incorrectly traded on the NYSE everyday

• 3 warranty claims for every new automobile

• 48,000 to 96,000 deaths attributed to hospital errors each year

• Cell Phone would be out-of-service (down) 54 hours a year

99.99966% Great (6σ)

• One hour without electricity every 34 years

• 1 misspelled word in all the books in a medium sized library

• 4,021 shares incorrectly traded on the NYSE everyday

• 1 warranty claim for every 980 new automobiles

• 17 to 34 deaths attributed to hospital errors each year

• Cell Phone would be down less than 2 minutes a year

Six Sigma Simplicity

Business Impacts of Variability

• Prevention Costs– Education and training– Safety– Controlling processes

• Appraisal Costs– Incoming inspection– Maintenance and calibration of

equipment– Process audits

• Internal Failure– Incorrect transactions– Things Done Wrong– Rework– Re-inspection – Late Delivery Times

• External Failures– Processing customer inquiries– Incurring penalties/claims – Lost sales

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Lean + Six Sigma Work Together

• Along with the Kaizen (waste reduction) process, the concept of ‘Six Sigma’ is another structured team approach for improving process performance

• It emphasizes the importance of identifying key critical inputs that effect your key outputs through statistical analysis

• It drives for perfection in those processes by reducing variation and/or moving the mean