#
Outside Arrangement of Orthogonal Array

The ideas of
SN Ratio
,
Two Step Analysis
,
and
Classification of factors
are made to realize
Robust Design
.
The outside arrangement of orthogonal array is used to realize these ideas.

##
Basic Style to Estimate Unevenness

The figure,
"Data analysis of two unevenness",
is the basic style to estimate unevenness.
In this case, same sets of conditions are repeated.

The repeat the set of condition is necessary to evaluate unevenness.
For example, we cannot divide the effects of "the unevenness by the repeat of A1"
and "difference between B1 and B2".
(General style of
Design of Experiments
often adopts the latter.)

##
Only Error Factor

The outside arrangement is used to evaluate
Error Factor
.

The figure,
"Outside Arrangement of Error Factor",
changes the level of the error factor.
The process of data analysis is same to "Data analysis of two unevenness".

Repeat of the experiment is not done because of the idea that "Unevenness is strengthened by the error factor."

##
Only Signal Factor

The other use is to evaluate
signal factor
.
The figure,
"Outside Arrangement of Signal Factor",
changes the level of the signal factor.

For example, V1 is
correlation coefficient
calculated by (D1, Y11), (D2, Y21), (D3, Y31).

More than 3 levels are necessary to evaluate the signal factor.

##
Both Error Factor and Signal Factor

The figure,
"Outside Arrangement of Error Factor and Signal Factor",
is to evaluate both factors.
When you study the
dynamic characteristics
by some books,
you may meet this table as the first step to learn.

SN ratio of dynamic characteristics in the page of "
Characteristics and SN Ratio
" is to evaluate only the signal factor.
But many books show the SN ratio for the mixed case of the error factor and the signal factor.

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