抄録
The design is carried out using the expression that described causation. The approximate expression of enough levels
in a necessary range is enough for it. The approximate expression is often a multivariate multinomial expression made by the
data which is acquired by an experiment plan. When the specific variable (hyper factor) in this expression is focused, another
multinomial expression based on focused variable can be constituted. After it is constituted, the necessary role is assigned for
focused variable, design is enabled. A designer has the freedom to decide which variable must be focused and decide which
role must be assigned for it. This paper discusses a design as free creative activity of engineer from this point of view.
