Six Sigma Flashcards
What does a Kano Diagram represent?
Customer Satisfaction
What are the three elements of a Kano Diagram?
- Order Qualifiers 2. More is better 3. Delighters
What does SIPOC stand for?
Suppliers Inputs Process Outputs Customers
What does DMAIC stand for?
Define, Measure, Analyze, Improve, Control
What does DMADV stand for?
Define, Measure, Analyze, Design, Verify
What does COPQ?
Cost of Poor Quality
What is CTQs?
Critical to Quality
What is LSL?
Lower Specification Level
What is USL?
Upper Specification Level
What is the definition of customer requirements?
The ares between the LSL and USL
What does sigma mean?
Standard Deviation
What does Mu mean?
The mean
What is the sigma?
The average distance of data points away from the centre of the data.
Over time variations develop in a process. how many sigma variations are added as standard?
1.5
Inputs are also known as?
x factors
Outputs are also known as?
y factors
Are inputs independent or dependent variables?
Independent
Are outputs independent or dependent variables?
Dependent (dependent upon inputs)
What is the formula for expressing output dependency?
y=f(x1,x2,etc)
In the formula y=f(x) what does y, f and x stand for?
y=output, f=function, x=inputs
What is the pareto rule?
80% of issues come from 20% of sources
What is the aim of the pareto rule?
To focus on the 20% which has the greatest impact
What does CTCs stand for?
Critical to Customer
How is customer value defined
Value = benefit-cost
What are the four types of costs of poor quality?
- Internal Failure - Defects before the items have been sent to the customer.
- External Failure - Defects after the item has been sent to the customer.
- Prevention Costs - Activities taken to prevent and improve quality.
- Detection - Appraisal Costs - Detection of defects after they occur.
What is the sweet stop for Cost of Poor Quality
A balance between investment in Quality and number of Defects.
Costs of poor quality can be hard or soft, name three of each category?
Hard =
a. Rework
b. Rejects/scrap
c. Increased inspection
Soft =
a. Damage to reputation.
b. Lost Sales.
c. Late deliveries
Give an example of a cost associated with Internal Failure?
Quality Department/Final Inspections
Give an example of a cost associated with External Failure?
Warrantys, Customer charge back cost
Give an example of a cost associated with Quality Prevention?
In-process error proofing devices, product redesign.
Give an example of a cost associated with Detection, Appraisal
Extra testing, Supplier audits.
Name some low cost quality improvement activities?
Employee engagement & ideas
Kaizen
Error Proof Design
Work standardisation
What key metrics focus improvement efforts on reduction in variation?
Defects per unit (DPU)
Defects per million opportunities (DPMO)
Parts per million defective (PPM)
Rolled Throughput Yield (RTP)/First Pass Yield (FPY)
What is the formula for Defects per unit?
Total defects/sample size
What is the formula for Defects per million opportunities?
Total Defects/Total Defect opportunities x 1m
What DPMO does a six sigma process achieve?
3.4 DPMO
What is the formula for Parts per Million Defective?
Total defected units/total opportunities x 1m
What is the formula for First Time Yield?
Total Units Passed/Total United Tested
What is the difference between first time yield and Rolled throughput yield (First Pass yield)?
First time yield is measured at the end of the process and shows total defects at the end of the process. Rolled throughput yield measures the percentage of time a unit passes each stage without failure.
What is another name for First Pass Yield?
Rolled Throughput Yield
What is the criteria required for estimating RTY?
Must be fewer than 10% defective items with more than 16 opportunities.
What is the formula estimating RTY?
RTY= e-DPU e to the power of DPU
In estimating RTY what is e calculated at?
=2.71828
What is Lean?
Lean is a philosophy - a set of principles, supported by a set of tools, designed to eliminate waste.
What are the three principles of Lean?
- Focus on adding value to the customer.
- Relentless pursuit of perfection through continuous improvement.
- Focus on the elimination of waste.
How are the lean philosophy activities defined?
- VA - Valued added (to the customer)
- NVA (but necessary)
- NVA.
How would a lean process be defined?
A lean process uses the minimum amount of time, material, people,space, energy needed to add value to product.
What are the 7 elements of waste?
TIM WOOD
Transport Inventory Motion Waiting Over production Over processing Defects
What two elements of waste are not included in TIM WOOD?
Unused Talent, Poor Safety
What is Gemba?
Go see at the scene, waste walk
What does 5s stand for?
Sort - Remove clutter
Set In Order - Store item correctly, set locations
Shine - Clean work area
Standardise - Set as the norm, enforcement
Sustain - Remain disciplined
What is a value stream map?
A value stream map is used for analysing current state vs designing future state, it includes C/T cycle time in each part of the process to identify waste opportunities.
With a normal distribution, at one standard deviation from the mean we would find:
The mode
A point of inflection
The median
A local maximum
Which of the following are true about RTY (select all that apply)
RTY includes losses from rework
RTY can be estimated from the number of defects per unit, if the number of defects is low
RTY is the sum of the yields at each step in the process
RTY is also known as first pass yield
RTY is the probability that that a process will complete all required steps without any failures
A Kanban control system primarily reduces which type of waste:
Overproduction Transport / Conveyance Over-processing Waiting Defects
In the value stream map shown on the ‘Test Question Resources (SSBB): DEFINE’ page, under ‘Image 1, what percentage of the lead time is value added?
100% 98 . 2% 36 . 1% 1 . 8% 0% Can’t tell
What is the English translation of the Japanese word “muda”?
The process of standardisation A schedule of local, team-based improvement events Mistake-proofing Sigma Waste
Quality is defined by?
Design Engineering, through the design specification
The customer
Conformance to ISO9001
The end-of-line inspection standards
Consistently achieving the product claims made in the sales brochure
Lean Six-Sigma financial savings come primarily from..?
Reducing the waste associated with process variation
Increased sales through higher quality products
Labour savings through increased productivity
Improved financial analysis
The following are examples of customers for a project (select all that apply).
A regulatory agency The local community A competitor The Shipping Department The company’s electricity supplier
Which of the following are examples of internal customers (select all that apply)?
Despatch A regulatory agency The Health and Safety Department The end user for our product Senior Management
Choose an answer to complete the sentence: In an organisation, the ___________ Champion would typically select projects to ensure that the CI programme aligns with business strategy.
Project
Product
Programme
Business
A Six Sigma process… (select all that apply):
Is not subject to 1 . 5-sigma drift over time
Usually requires process redesign to achieve
Has two ranges, each of 3 standard deviations
Has a long-term expected performance of 3.4 defects per million opportunities
Is usually prohibitively expensive, and therefore only worth pursuing in safety-critical industries
Has 6 standard deviations between the mean output and the closest specification limit
The difference between CTCs and CTQs is…?
The level of criticality
“Must-haves” versus “nice-to-haves”
What’s required by our customers versus what’s important in our processes
There is no difference
One is the benefit seen by the customer, the other is the cos
Value is defined as?
Benefit minus cost for the customer Benefit minus cost for any given stakeholder The quality performance of the process Customer satisfaction Sales price minus cost
True or False: Voice of the Business describes where value is being diminished, where meeting customer requirements is causing pain.
True
False
Choose an answer to complete the sentence: A Six Sigma project improves process performance by finding and controlling the ______________ (or input) variables.
independent
dependent
defined
most important
Six Sigma is based on the premise that poor quality is caused by?
Poor workplace organisation Waste Variation Lack of management support People
True or false: The process shown on the ‘Test Question Resources (SSBB): DEFINE’ page, under ‘Image 2, is running at a 4-sigma level, because 4 standard deviations will fit between the specification limits
True
False
Which of the following are measures of variation in a process (select all that apply)?
Mean Sigma Variance Standard deviation Interquartile range
A process has a long-term first pass yield of 99.4%. What sigma level is it operating at?
9
4
6
3
When selecting an area of the business to focus on for improvement projects, the Quality Champion is most likely to use..?
A box plot A Pareto chart A normal distribution An SPC chart All of the above
True or False: A tool for mapping the high-level process and defining the scope is known as a ‘SIPOC’.
True
False
A project team in a large company is given the task of “halving the warranty bill for all products”. This is an example of:
A well-defined project scope Boil the ocean Micro-focused Solution in mind Multiple focuses
Which of the following are preventative costs of poor quality (select all that apply)?
Warranty Containment Product redesign Supplier certification Inspection
A Service Manager wants to focus his efforts on warranty improvement. Based on the image shown on the ‘Test Question Resources (SSBB): DEFINE’ page, under ‘Image 3’, which products should a project focus on, in order to address at least 50% of the warranty costs?
Product A Product D Products A & D Products A, B and D All products
True or False: In Lean philosophy, the 7 wastes are Transport (conveyance), Inventory, Motion, Waiting, Defects (correction), over-processing and overproduction
True
False
Uploading and downloading information is an example of which waste?
Time
Production
Processing
Transport (or conveyance)
Which of the following are classified as hard (rather than soft) costs (select all that apply)?
Warranty Late deliveries Rework Excess inventory Lost sales
The Y measure for a process is the…?
Control variable
Dependent variable
Independent variable
Attribute variable
What is Takt Time?
Baton, Pulse or Beat Time
Name 5 types of process maps?
Linear, Swim Lane, SIPOC, Value Stream Map, Spaghetti Map
What does RFT stand for?
Right First Time
What does a spaghetti map show?
Movement of product, people, equipment.
What are the rules of input?
Must be specifically linked to the primary or secondary metric.
RUMBA is the rule of inputs, what does it stand for?
Reasonable, Understandable, Measurable, Believable, Achievable.
What are the three input classifications?
Controllable, Procedural, Uncontrollable (Noise)
What is the aim of a cause and effect diagram?
The aim is to generate a list of Xs
What are two types of Cause and Effect Diagrams?
Fishbone and 5whys
What is the purpose of the X-Y matrix?
To determine the significance of each x-y relationship
What weighting is given to the primary metric in the X-Y matrix?
10
What does FMEA stand for?
Failure Modes Effects Analysis
What is the purpose of the FMEA?
To analyse the ways in which a process can fail.
What does RPN stand for?
Risk Priority Number
How is the RPN calculated?
Severity x Occurrence x Detection
What is meant by qualitative data?
Subjective data, used to classify or judge
What is meant by quantitative data?
Data with numbers, used to measure.
What types of quantitative data are there?
Discrete, continuous.
What types of qualitative data are there?
attribute, nominal, ordinal
What is the difference between nominal/ordinal data?
Nominal has no logic order in the data, Ordinal does
What is the difference between discrete and continuous data?
Discrete - count (non divisible) , Continous = measure, finer and finer detail.
What is the mean?
Average, pivot point on a graph
What is the median?
The middle value when data arranged in order
What is the mode?
The most common value
What is the spread on a data set?
The range
What is the interquartile range?
The range between the 25th and 75th percentile
What is the standard deviation?
The average distance of the data points from the mean.
What happens to the variance with greater spread?
Greater variance
What is the minimum sample size for statistical relevance?
30
What chart would be used to check for normal distribution of a data set?
Histogram
What does it mean if a p value was less than 0.05?
Statistical difference exists in the data set.
What is a dot plot graph and how is it used?
Plots dots on a graph to indicate shape of sample and shows unusual data points.
What is brushing and what is it used for?
Shows each individual data point on a scale, indicates shape of sample and shows unusual data points.
What is a box plot graph?
The box on the visualization contains the interquartile range, middle 50% with the whiskers containing the upper and lover 25% of the data set.
What is a Time series plot?
Shows the values over time on an x axis.
What is the use of a scatter-plot?
Shows the relationship between two variables.
What is measurement systems analysis?
measurement of true value + error from operator, equipment or method to show the measured value.
What is the purpose of Measurement systems analysis?
The determine how accurate and precise our method of measurement is.
What are the causes of measurement error?
Poor Training, Poor Sampling, Poor procedures, inaccurate, insufficient or non calibrated measuring devices and awkward or time consuming measurements.
What is the difference between accuracy and precision?
Accuracy is how close the measured values are to the true values. Precision is the variation seen between the repeated measurements of the same thing.
What is accuracy bias?
The distance between the true value and the measured value.
What is accuracy linearity?
The accuracy of the measurement across data values.
What is accuracy resolution?
The ability of the measurement to give the detail required.
What is accuracy stability?
the accuracy of the measurement method over time.
What is the minimum number of runs/parts, operators and measurements required in a measurement systems analysis for continuous data?
Runs/Parts =10
Operators = 3
Measurements = 2 per par, per operator.
Gauge r&r is the percentage of variation that comes from the measurement, what is the acceptable percentage of variation?
30%, Ideally 10%
What is the minimum number of runs/parts, operators and measurements required in a measurement systems analysis for quantitative data?
Runs/Parts =30
Operators = 3
Measurements = 2 per par, per operator.
What is the definition of reproduciblility?
% of parts/sample where the appraisers agree with each other, give the same answer.
What is the kappa score?
The kappa statistics tell us how much better the measurement system is than random chance.
