Quality Progress - March 2018 - 48

Solving quality quandaries through statistics

Statistics Spotlight
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RANDOMIZATION

At Random
The rationale behind randomization, and options when up against constraints
by Christine M. Anderson-Cook

When I was a faculty member in the department of statistics
at Virginia Tech more than a decade ago, I sometimes taught
the "Statistical Methods for Scientists and Engineers" course.
This course was primarily taken by graduate students from other
departments who wanted to learn enough statistics to be able
to effectively design and analyze an experiment as part of their
thesis or dissertation work.
As part of the course, I always emphasized the importance
of randomization to protect against the unexpected and to
ensure the validity of the interpretation of results for establishing
causality.
After taking the stats methods class, one chemical engineering
graduate student made an appointment with me in the statistics
consulting center. He wanted help designing an experiment for
his master's thesis. After discussing the experiment's goals, which
factors to manipulate and their ranges, I provided him with a
designed experiment (in this case, a 16-run 24 factorial design)
that matched his needs.
As was my usual habit, we talked through the design characteristics with the design in standard order (Figure 1-part a), and
I provided another version of the design in randomized order
(Figure 1-part b). I began to give him instructions about the
implementation of the proposed design based on the randomized design table. He interrupted and said: "Oh, come on. You
don't really expect me to do this experiment with that randomization thing. That's just some theory that you statisticians tell us
in classes."
I must have looked suitably shocked: This was a student who
had done well in my class, and by all accounts had taken in my
admonition to randomize experiments seriously when completing
class assignments and tests. I asked, "Why would randomization
not be relevant to your experiment? Don't you remember the
advantages of randomization that we discussed in class?"

48 QP

March 2018 ❘ qualityprogress.com


http://www.qualityprogress.com

Table of Contents for the Digital Edition of Quality Progress - March 2018

Seen and Heard
Expert Answers
Progress Report
Mr. Pareto Head
Career Coach
My Quality Story
In the Right Direction
A Different Kind of BBQ
Gaining Ground
Impeding Progress
Innovation Imperative
Statistics Spotlight
Standard Issues
Marketplace
Footnotes
Back to Basics
Quality Progress - March 2018 - INTRO
Quality Progress - March 2018 - cover1
Quality Progress - March 2018 - cover2
Quality Progress - March 2018 - 1
Quality Progress - March 2018 - 2
Quality Progress - March 2018 - 3
Quality Progress - March 2018 - 4
Quality Progress - March 2018 - 5
Quality Progress - March 2018 - Seen and Heard
Quality Progress - March 2018 - 7
Quality Progress - March 2018 - Expert Answers
Quality Progress - March 2018 - 9
Quality Progress - March 2018 - Progress Report
Quality Progress - March 2018 - 11
Quality Progress - March 2018 - 12
Quality Progress - March 2018 - Mr. Pareto Head
Quality Progress - March 2018 - Career Coach
Quality Progress - March 2018 - 15
Quality Progress - March 2018 - My Quality Story
Quality Progress - March 2018 - 17
Quality Progress - March 2018 - In the Right Direction
Quality Progress - March 2018 - 19
Quality Progress - March 2018 - 20
Quality Progress - March 2018 - 21
Quality Progress - March 2018 - 22
Quality Progress - March 2018 - 23
Quality Progress - March 2018 - A Different Kind of BBQ
Quality Progress - March 2018 - 25
Quality Progress - March 2018 - 26
Quality Progress - March 2018 - 27
Quality Progress - March 2018 - 28
Quality Progress - March 2018 - 29
Quality Progress - March 2018 - 30
Quality Progress - March 2018 - 31
Quality Progress - March 2018 - Gaining Ground
Quality Progress - March 2018 - 33
Quality Progress - March 2018 - 34
Quality Progress - March 2018 - 35
Quality Progress - March 2018 - 36
Quality Progress - March 2018 - Impeding Progress
Quality Progress - March 2018 - 38
Quality Progress - March 2018 - 39
Quality Progress - March 2018 - 40
Quality Progress - March 2018 - 41
Quality Progress - March 2018 - 42
Quality Progress - March 2018 - 43
Quality Progress - March 2018 - Innovation Imperative
Quality Progress - March 2018 - 45
Quality Progress - March 2018 - 46
Quality Progress - March 2018 - 47
Quality Progress - March 2018 - Statistics Spotlight
Quality Progress - March 2018 - 49
Quality Progress - March 2018 - 50
Quality Progress - March 2018 - 51
Quality Progress - March 2018 - 52
Quality Progress - March 2018 - 53
Quality Progress - March 2018 - Standard Issues
Quality Progress - March 2018 - 55
Quality Progress - March 2018 - 56
Quality Progress - March 2018 - 57
Quality Progress - March 2018 - Marketplace
Quality Progress - March 2018 - 59
Quality Progress - March 2018 - Footnotes
Quality Progress - March 2018 - 61
Quality Progress - March 2018 - 62
Quality Progress - March 2018 - 63
Quality Progress - March 2018 - Back to Basics
Quality Progress - March 2018 - cover3
Quality Progress - March 2018 - cover4
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