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The basic design points are augmented with
additional internal points:
The constraints on the mixture
do not create a triangular region for the
experiment. The illustration shows a three
component design:
A type of design where the design points
are placed on a 'lattice':
Constraints on the component proportions
still allow the experimental region to be
represented as a triangle. The illustration
shows a three component design:
Mixture designs are a type
of type of experimental design that is
used to find the best composition when
there is a mixture of ingredients. Mixtures
are different from other types of experimental
design because the proportions must add
up to 100%. Thus increasing the level
of one constituent must reduce the level
of the others.
The analysis is complex
and so a software package, such as Minitab,
would invariably be used to analyze the
results. For other types of experimental
design, not involving mixtures refer to
the topic on Design of Experiments.
A Type of mixture design with
points at the corners, the midpoints of
the sides, and the center:
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