Lean Six Sigma

Question 1

DMAIC - Define

Answer 1

Prioritize projects based on business impact and alignment with organizational imperatives. Lean Six Sigma projects start by capturing the voice of the customer:
A) Organize a team to improve the process of interest, and develop a Charter to guide team actions.
B) Identify the customer(s) and critical customer requirements (Voice of the Customer).
C) Determine what “success” looks like for the improvement project.
D) Create a process map of the process to develop process knowledge - there are many formats.

Question 2

DMAIC - Measure

Answer 2

Measurements drive the Lean Six Sigma improvement process - what gets measured gets done!
A) Define performance standards
B) Identify potentially significant Process Inputs (Xs)
C) Validate the measurement system
D) Establish baseline performance with regard to customer requirements (called Capability).

Question 3

DMAIC - Analyze

Answer 3

Analytical tools are used to dissect the root cause of process variability and separate the vital few inputs from the trivial many.
A) Identify significant characteristics (inputs, or Xs) and establish process capability.
B) Define performance targets for significant characteristics (inputs, or Xs).
C) Identify the root cause of process variation.
D) Use statistical methods to verify the effectiveness of alternatives.

Question 4

DMAIC - Improve

Answer 4

The Improve phase turns analysis into action.
A) Identify and evaluate potential solutions.
B) Implement short term countermeasures.
C) Implement long term corrective actions.
D) Identify systemic indirect effect and unintended consequences of improvement actions.
E) Establish operating tolerances for new processes.

Question 5

DMAIC - Control

Answer 5

After implementing improvement actions, the Control step verifies results and consolidates the gains:
A) Verify corrective actions and validate new measurement systems.
B) Determine new process capability.
C) Establish and implement control plan.
D) Share best practices and lessons learned.

Question 6

SIPOC Map

Answer 6

dentifies Suppliers, Inputs, Outputs, and Customers - High level starting point - used in most DMAIC projects

Question 7

Flow Chart

Answer 7

Shows decision points and If/Then logic - Displays procedures and logic of process

Question 8

Deployment Flow Chart

Swimlane Chart

Answer 8

Identifies functional responsibilities - Communicates who does what

Question 9

Value-Added Flow Chart

Answer 9

Separates Value-Added from Non-Value-Added operations. - Identifies waste of many types. Stratifies time.

Question 10

Spaghetti Diagram

Answer 10

Shows physical flow of material and/or information. - Illustrates physical complexity, distance traveled, cycle time

Question 11

Value Stream Map

Answer 11

Identifies physical flow of materials and information. Quantifies inventory levels, process characteristics and control mechanisms. - Detailed map for lean improvement projects and Kaizen events.

Question 12

System Diagram

Answer 12

Focused on systemic cause and effect - shows reinforcing and balancing forces along with unintended consequences. - Examines behaviors behind process performance - non-linear.

Question 13

Cause and Effect Matrix

Answer 13

used to prioritize the process inputs (causes, or X’s) that have been identified as potentially contributing to an Effect (Y). This action usually leads to selection of inputs for data collection and subsequent analysis.

Question 14

Benefits of C & E Matrix

Answer 14

1) The C & E Matrix provides a way to prioritize potential causes based on the number of CTQC’s affected and the strength of the relationship between potential causes (X’s) and effects (Y’s).
2) It appeals to team members who are more comfortable with ranking techniques than visual tools.
3) The matrix also brings together the CTQC’s from the Tree Diagram and the process steps identified during process mapping. This promotes “process thinking” and provides a logical linkage between the tools.

Question 15

The steps required to complete a Cause & Effect Matrix

Answer 15

Step 1: Place the CTQC’s (from a Tree Diagram) along the left side of the cause and effect matrix. These are the Effects.
Step 2: Rank the importance of each of the Effects, or CTQC’s, from the customer’s point of view. (Note: the template provided below assigns the following values: H=5, M=3, L=1)
Step 3: Place the Process Inputs (X’s) along the top of the matrix. These are the Causes, and they will have been identified through process mapping and brainstorming, possibly with help from a Fishbone Diagram.
Step 4: Assign a correlation factor between the Causes and the Effects based on experience and process knowledge.
Step 5: Evaluate the output and check for consistency.
Step 6: Choose which factors you wish to analyze further. (Note: Overall Input Importance Score is the product of the Importance Ranking x the Correlation Factor)

Question 16

Stability

Answer 16

refers to the capacity of a measurement system to produce the same values over time when measuring the same sample. As with statistical process control charts, stability means the absence of “Special Cause Variation”, leaving only “Common Cause Variation” (random variation).

Question 17

Bias, also referred to as Accuracy

Answer 17

is a measure of the distance between the average value of the measurements and the “True” or “Actual” value of the sample or part. See the illustration below for further explanation.

Question 18

Linearity

Answer 18

is a measure of the consistency of Bias over the range of the measurement device. For example, if a bathroom scale is under by 1.0 pound when measuring a 150 pound person, but is off by 5.0 pounds when measuring a 200 pound person, then the scale Bias is not constant and it will be important to understand if this Bias changes in a linear fashion or not. Linearity may be expressed as an index, or as a percentage of the process variation.

Question 19

Location (Average Measurement Value vs. Actual Value)

Answer 19

1) Stability
2) Bias, or Accuracy
3) Linearity

Question 20

Variation (Spread of Measurement Values - Precision)

Answer 20

1) Repeatability

2) Reproducibility

Question 21

Repeatability

Answer 21

assesses whether the same appraiser can measure the same part/sample multiple times with the same measurement device and get the same value.

Question 22

Reproducibility

Answer 22

assesses whether different appraisers can measure the same part/sample with the same measurement device and get the same value.

Question 23

Population

Answer 23

The entire process output, or collection of objects about which we wish to draw a conclusion.

Question 24

Sample

Answer 24

The subset chosen to represent the population.

Question 25

Random Sample

Answer 25

A sample drawn such that every member of the population has an equal chance of being selected.

Question 26

Parameter

Answer 26

A quantity associated with the population. Designated by Greek or capital Roman letters. Examples: P (proportion), "delta" (average), "sigma" (standard deviation)

Question 27

Statistic

Answer 27

A quantity calculated from the sample. Designated by lower-case Roman letters. Example: p (proportion), ybar (average), s (standard deviation).

Question 28

Descriptive statistics

Answer 28

aim to describe and summarize the important features of a population or process. (i.e. pie, bar and line graphs.)

Question 29

Inferential statistics

Answer 29

use sample data to help make comparisons among, or draw inferences about the effects of different solutions or treatments on the overall population. When the entire population cannot be measured, a smaller sample of data is used to infer, or estimate, the characteristics of the wider population. (i.e. Regression analysis, hypothesis tests and experimental design)

Question 30

Enumerative Studies

Answer 30

which aim to answer questions about the current population like “how many?” or “in what proportion?” The focus is historical rather than predictive.

Question 31

Analytical Studies

Answer 31

seek to answer questions like “why?” or “what are the causes of?” and aim to generalize the results to future states of the population. Analytical studies are conducted to understand the behavior of a process over time with the intention of identifying relationships between cause and effect which could impact future performance (predictive as well as historical perspective).

Question 32

Levels of the data hierarchy

Answer 32

Level 1: Nominal Level 2: Ordinal Level 3: Counts Level 4: Continuous

Question 33

Discrete measurement, often termed as Attribute data

Answer 33

Sort or count items based on attributes, such as the presence/absence of defects, quality perceptions, occurrence of an event, etc.

Question 34

Continuous measurements, often termed Variable data

Answer 34

Can take on infinite values within any two fixed points

Question 35

Discrete Nominal

Answer 35

Groups are labels, no order: (i.e., profession, region, color, type of defect, etc.

Question 36

Discrete Ordinal

Answer 36

Groups are a logical order: (i.e., small, medium, large)

Question 37

Discrete Counts

Answer 37

Number of items or events: (i.e., accidents, sales per week, errors on page, etc.)

Question 38

Continuous

Answer 38

Measurements are made along a continuum: (i.e., gas milage, concentration in a sample, speed of pitch, etc.)

Question 39

Genichi Taguchi's - Quality Loss Function

Answer 39

stipulates that the total loss to society from poor quality increases in a geometric fashion as variability increases.

Question 40

Efficiency metrics

Answer 40

measure the amount of input necessary to achieve a given output.

Question 41

Effectiveness metrics

Answer 41

a direct measure of how well customer expectations are met.

Question 42

Xbar & S Chart

Answer 42

Xbar & S charts allow you to track both the process level and process variation at the same time, as well as detect the presence of special causes.

Question 43

Xbar & R Chart

Answer 43

Xbar & R charts allow you to track both the process level and process variation at the same time, as well as detect the presence of special causes.

Question 44

XmR or I & MR Chart

Answer 44

XmR charts allow you to track both the process level and process variation at the same time, as well as detect the presence of special causes.

Question 45

C Chart

Answer 45

C charts track the number of defects and detect the presence of special causes. Used to chart the number of defects when the subgroup size is constant (although usually greater than 50). This chart assumes that the process has a Poisson distribution. 

Question 46

nP Chart

Answer 46

nP charts track the number of defectives and detect the presence of special causes. Used to chart the number of defective units when the subgroup size is constant (usually greater than 50). This chart assumes that the process has a binomial distribution.

Question 47

U Chart

Answer 47

U charts track the number of defects per unit sampled and detect the presence of special causes. Used to chart the number of defects per unit when the subgroup size is variable or constant. This chart assumes that the process has a Poisson distribution.

Question 48

P Chart

Answer 48

P charts track the proportion defective and detect the presence of special causes. Used to chart the fraction defective when the subgroup size is variable or constant (although usually greater than 50). This chart assumes that the process has a binomial distribution. 

Question 49

Application of Multiple Proportion Chi-Squared Test

Answer 49

This type of inference is used during the Analyze or Improve phases of a Lean Six Sigma project when it is desired to know if there is a difference among multiple groups with respect to a binary (Yes/No) characteristic or attribute.