2. Defining the screening plan

The screening technique is used to determine the influential elements in an initial set of factors. It is a selection or screening process. Generally speaking, any variation in a factor induces changes in response values. This is true for all factors, but on different scales. We compare variations in the response elicited by two sources:

• variations in the factor studied ;

• variations in quantities considered to have no effect on response (noise).

A statistical test is performed to reject the hypothesis that the factor does not induce response variations significantly greater than those caused by noise. Equivalently, a factor is considered influential (or determining) if its action on the response studied is statistically greater than a certain level set by the experimenter....