Simplex-Centroid Design
This mixture design can be used for 3 to 8 components. Simplex implies that all component ranges are equal. A simplex-centroid design consists of all points that are equally weighted mixtures of 1 to q components.
Included are permutations of:
Pure blends: (1, 0, …,0)
Binary blends: (1/2, 1/2, 0, …,0)
Tertiary blends: (1/3, 1/3, 1/3, 0, …,0) …
and so on to the overall centroid: (1/q, 1/q, …, 1/q)
This design differs from a simplex-lattice design. It cannot be used to estimate the full cubic model, but can be used to estimate a special cubic model.
Mixture Components: How many components are involved in this experiment?
Note
Fillers may be components too unless their proportion of the mixture is held constant.
Note
Components that will remain a constant proportion of the total can be added to the design by setting the low and high limits to the same value.
Total: The sum of all the components must equal the total for all runs.
Units: (optional) All components must use the same units of measurement.
Note
Common units of measure include direct amounts (mass or volume), weight %, % volume by weight, and molecular equivalents.
Name: Provide names for the components to help with later documentation
Low: The lowest value a component can take (often zero).
High: The highest value a component can take (no larger than the Total)
Edit Constraints button: Click this button to impose additional constraints on component combinations allowed. For more details use the help button on the Edit Constraints dialog.
Adding a constraint will generally make the design non-simplex and force the experimenter to use an optimal design instead.