Lecture 9 - Design of Experiments (DoE)

Question 1

What does DoE stand for?

Answer 1

Design of Experiments

Question 2

DoE is defined as…

Answer 2

A series of purposeful changes to the process inputs (factors)
in order to observe the corresponding changes in the outputs (responses)

Question 3

Key Processes +
______ Processes +
______ Processes = Output

Answer 3

Key processes +
Controlled processes +
Uncontrolled Processes = Output

Question 4

The objectives of DoE is to…

Answer 4

• Determines which factors (inputs) have an effect on response average, variability, and those which do not
• Gain maximum amount of information with minimum resources
• Validate Results
• Optimise the process

Question 5

In DoE, when we “Optimise the process” means…

Answer 5

Improve performance characteristics, reduce costs and time associated with product development and production

Question 6

Give three negatives of using a OFAT (One Factor at at Time) approach

Answer 6

• Expensive and Time Consuming
• Unable to evaluate interaction effects
• Can miss optimum settings

Question 7

What are the main advantages to DoE

Answer 7

• Efficiency (Reduced time and resources to conduct experiments)
• Evaluates interaction effects between the factors

Question 8

DoE should ONLY be used after the application of…

Answer 8

IPO / PF / CE / SOP / FMEA

Question 9

if we had 20 factors, each of which had 4 different possible values, how many combinations of factors would we need to evaluate if we were to use the OFAT approach?

Answer 9

Using “One Factor at a Time” we would need to evaluate
4^20 = 1,099,511,627,776 samples.
Therefore OFAT is a very inefficient process!

Question 10

Strategies for Experimentation include

Answer 10

• Screening to separate contributing and non contributing factors (Factorial Designs)
• Optimisation to be able to predict the response for a given combination of factors (Response Surface Designs)

Question 11

Factorial Designs are…

Answer 11

• Good preliminary experiments which is separated into two types of factorials:
Full and Fractional

Question 12

“Full” factorials involve…

Answer 12

testing every combination of factor levels

Question 13

“Fractional” factorials are…

Answer 13

used to find the “vital view” significant factors out of a large group of potential factors

Question 14

DoE Terminology:

Controlled Experiment means…

Answer 14

A study where treatments are imposed on experimental units, in order to observe a response

Question 15

DoE Terminology:

Factor means…

Answer 15

A variable that potentially affects the response

Question 16

DoE Terminology:

Treatment means…

Answer 16

A combination of one or more factors

Question 17

DoE Terminology:

Levels means…

Answer 17

The values a factor can take on

Question 18

DoE Terminology:

Effect means…

Answer 18

How much a main factor or interaction between factors influences the mean response

Question 19

DoE Terminology:

Replicates means…

Answer 19

When you repeat your experiment design a 2nd, 3rd, 4th etc time.
It is NOT the same as repeated measurements!

Question 20

What are the 6 steps to the DoE Process?

Answer 20

1. Identifying the opportunity / problem variable to understand (Improve)
2. Defining you experiment
3. Planning your experiment for implementation
4. Conducting your experiment
5. Analysing your experiment
6. Implementing Action Plan

Question 21

True / False?
The general scenario for performing a DoE for non-industrial processes is the
same for industrial processes

Answer 21

True

You still need to understand your customer, products and processes.

Question 22

What is the fundamental difference between DoE for industrial purposes vs non-industrial purposes?

Answer 22

In an industrial process you are measuring things

In a non-industrial process you are measuring people