Industrial Statistics with Minitab

28.1 Matrix Design Creation and Data Collection

Example 28.1:

In a chemical reaction two components (Co1 and Co2) are mixed at a certain temperature (T) and speed (rpm). Among the reaction products that are obtained, there is one that is unwanted (Prod); the aim is to reduce its production to a minimum quantity.

The lasting time of the reaction is already known and remains constant, but it is decided to carry out a central composite design to see how the factors T, Co1, Co2 and rpm affect the response variable Prod.

Central composite designs are widely used because they allow us to plan the experimentation in two stages:

• A two level factorial design with centre points is carried out, checking for the need of quadratic terms.
• If a quadratic term is needed, ‘star’ points are added to allow the estimation of the pure quadratic terms.

Stat > DOE > Response Surface > Create Response Surface Design

28.1.1 Designs

Blocks: Choose the number of blocks. Usually, each block corresponds to sequentially performed experiments. For example, if experiments are carried out in two different ...