Analysis of a mixture design
Analyzing mixture design data allow determining the optimal formulation of a product. Available in Excel using the XLSTAT statistical software.
What is mixture design analysis
The analysis of a mixture design is based on the same principle as linear regression. The major difference comes from the model that is used. Several models are available.
By default, XLSTAT associates a reduced model (Simplified Canonical Model) to centroïd simplexes. However, it is possible to change the model if the number of degrees of freedom is sufficient (by increasing the number of repetitions of the experiments). Otherwise, an error message will be displayed informing you that the number of experiments is too small for all the model coefficients to be estimated.
To fulfil the constraint associated to a mixture design, a polynomial model with no intercept is used. We distinguish two types of models, simplified (special) models and full models (from level 3).
Estimation of these models is done with classical regression.