Module 5 - Six Sigma Quality Analysis & Process Improvement

Question 1

What is process outcome

Answer 1

How the output of the process is characterized

Question 2

A “stable” process is one that is: __ and __

Answer 2

unchanged over time and in statistical control

Note: There will still be random variation

Question 3

A capable process is one whose outcomes:

Answer 3

meet its goals or objectives

Question 4

Analyzing process capability is impossible if it is __, because…..

Answer 4

the process is unstable because such processes are unpredictable

Question 5

Why do decision makers in services often react unnecessarily to random variation and what harm does this cause? (explain)

Answer 5

Humans are not naturally good at making decision in the presence of random variation. Humans see changes in outcomes and immediately assume that the process has changed. When reacting to random variation, we may initiate a search for root cause of a change when, in fact, no change has occurred. We may end up changing a perfectly good process. This action could disrupt employees’ ability to serve customers and eventually spread “fear” within an organization.

Question 6

How is acceptance sampling performed? (describe)
Name a con.

Answer 6

(1) A sample of parts is inspected to determine how many conform to design specifications.
(2) Based on these results, the batch of parts from which the sample was drawn was either passed on to the next stage of production or the entire batch was subjected to a “100% inspection.”

Cons: not designed to find the root cause of poor quality

Question 7

Total Quality Management (TQM) is __ oriented
It was developed by __

Answer 7

process

Demming

Question 8

Why is acceptance sampling a poor process improvement tool?

Answer 8

Because it is done after the process is run (often much later), it is typically done by inspectors who may not be familiar with the process, and it does not maintain the order of production. Therefore, it is ineffective at identifying root cause of problems.

Question 9

DPMO

Answer 9

defects per million opportunities

Question 10

Why would the Six Sigma quality metric be ineffective as a universal quality goal?

Answer 10

Because not all products are similar in complexity to those found at Motorola. Some applications (e.g., high volume with a high cost of defects) may warrant a stricter goal, while other applications (e.g., simpler commodity products) may warrant a less strict goal.

Question 11

MBO

Answer 11

management by objectives

Question 12

Statistically speaking, why is it difficult to create a fair bonus system based on process outcomes?

Answer 12

Because of the impact of random variation of outcomes. An outcome may not meet the objective even though the process is acceptable (and vice-versa).

Question 13

What’s the formula for customer satisfaction?

Answer 13

Satisfaction = performance - expectations

Question 14

Process outcomes can be __ or __

Answer 14

Tangible or intangible

Question 15

Two important concepts in the statistical analysis of quality are __ & __

Answer 15

process stability
&
process capability

Question 16

According to Deming, when the MBO approach is used in a quality system, it is flawed for a number of reasons.

Answer 16

1-it does not consider the impact of random variation.
2-it usually leads to managers gaming the process
3-it fails to recognize that performance is mostly dictated by the system, not the individual employees.

Question 17

What’s the difference between a stable and capable process?

Answer 17

Stable - process is predictable (unchanging and statistically controlled)
Capable - process meets its goals

Question 18

Statistical control charts were developed by: __

The basis of these rules is: __

It is __ oriented

They are used to determine if a process is __

They recognize that outcomes are subject to __

Answer 18

Walter Shewhart

normal distribution

process-oriented

stable

random variation

Question 19

___ was based on the process characteristics found at Motorola

It was developed to replace ___

Answer 19

six sigma

TQM (Total Quality Management)

Question 20

Today, six sigma seeks to make improvements based on projects whose benefits are __ __

Answer 20

Financially quantifiable

Question 21

For control charts,
UCL =
Center Line =
LCL =

Answer 21

UCL = µ + 3σ
Center Line = µ = p-bar
LCL = µ - 3σ

Question 22

σ formula on control chart
what is p?
what is n?
what is UCL and LCL?
Note: a proportion could never be less than __

Answer 22

σ = sq.rt { [ p * (1 - p) ] / n }
where
p = the likelihood of success
n = the sample/subgroup size
UCL = p + 3σ
LCL = p - 3σ
0%

Question 23

The most popular Shewhart rules for detecting an out of control process are:

Answer 23

1. 1 point exceeding any 3-sigma limit
2. 2 of 3 consecutive points beyond 2-sigma limits
3. 4 of 5 consecutive points beyond 1-sigma limits
4. 8 consecutive points on the same side of the center line
5. 10 of 11 consecutive points on the same side of the center line.

Question 24

On a control chart, would it be a good idea to show the objective as a horizontal line?

Answer 24

No. The presence of such a line would imply that the organization’s goal is to have each outcome exceed the objective, which is a de-facto MBO approach.

Question 25

On a P Chart, if the sample size were increased, the control limits: __
If the sample size decreased, the control limits: __

Why?

Answer 25

would become more narrow
would become wider

If you take larger samples from each batch (e.g., 50M items), you get a more accurate picture of the true proportion of defective items in that batch. The control limits on the chart would be narrower because you have a more precise estimate

Question 26

Can a process be in control but making a significant number of nonconforming parts?

Answer 26

Yes. When a process is in control (i.e., stable) it may still be off target and/or it may have a high level of natural variation relative to the product specifications.

Question 27

Six Sigma addressed a problem stemming from increased __

How does OFD relate?

Answer 27

product complexity

When a product becomes more complex, the number of OFDs increases. (OFD = opportunities for defects)

Question 28

Six Sigma seeks to maximize profits by __ __ to eliminate defects.
It focuses on __ increases as criteria for success

Answer 28

reducing variation
revenue

Question 29

Six Sigma uses a DMAIC structure. This stands for:

Answer 29

D - define the problem (and everything else about the project)
M - measure the space (gather info, describe current process)
A - analyze the current process to find where improvements should be made
I - improvement ideas (a list of them to solve the problem)
C - control (action plan to confirm & sustain improvements)

Question 30

Name the following for Lean and Six Sigma for:
1 - type and length of project
2 - project focus is to improve __ by __
3 - project is selected based on which will:
4 - analysis techniques are geared towards
5 - begins with:

Answer 30

Lean:
1- quick Kaizen projects in a few days; team works full time
2- customer service by minimizing wasteful practices
3- removes wastes, add value for customers
4- intuitive & descriptive displays, root cause analysis, mistake proofing
5- brainstorming session
Six Sigma:
1- deliberate projects over months; formal/disciplined DMAIC structure
2- customer service by minimizing variation & errors
3- decrease costs or increase revenue
4- statistical data analysis, controlled experiments, optimization
5- executive education & extensive training

In general:
- Lean is simple, quick and removes waste or adds value. Qualitative.
- Six Sigma is long, complex, and removes costs or adds revenue. Quantitative.

Question 31

Each Lean Six Sigma project should include three stages

Answer 31

Project Initiation, Project Execution, and Project Communication

Question 32

These generally mean what?
µ
σ

Answer 32

mean
standard deviation

Question 33

Control charts are used to determine if:

If so, it will show a __ pattern

Answer 33

a process is stable

random

Question 34

If a process does not achieve six sigma quality,

Answer 34

its variation must be reduced or its specifications must be relaxed

Question 35

True or False: If a company makes a product with 6-sigma quality, then these products would have a defect rate no worse than 3.4 defects per million products sold?

Answer 35

False. The 6-sigma metric applies to each OPPORTUNITY for defect, NOT the final PRODUCT

Question 35

Lean Six Sigma combination team should be a group of __ members

Answer 35

6-12

Question 35

What is DMAIC used for?

Answer 35

It’s a framework for managing a project