Modeling
Experimental planning in the food industry

Assigning the value " – 1" to the low level and "+ 1" to the high level of each factor amounts to making a change of unit of measurement and a change of origin. When a factor A varies from A₁ to A ₂ , the origin is equal to A ₀ = 1/2 (A ₁ + A ₂). The transition from the variable "A" to the reduced centered variable "x" is made by the following formula:

where the pitch p = A ₂ – A ₀ .

The variable x varies from – 1 to + 1.

The aim of this paragraph is to give a mathematical model for expressing the response variable y as a function of the quantities x of the reduced-centered variables corresponding to the factors under study.

In a two-factor design, let's assume that each factor acts linearly....