Response great curvature domain

Investigation of the Great Curvature Domain of the Response Surface Sequential Experimental Planning... 

The example shown above, introduces the necessity for a statistical investigation of the response surface near its great curvature domain. We can establish the proximity of the great curvature domain of the response surface by means of more complementary experiments in the centre of the experimental plan (xj = 0,X2 = 0,...Xij = 0). In these conditions, we can compute y, which, together with Pq (computed by the expression recommended for a factorial experiment... 

It is well known that the domains of the great curvature of the response surface are characterized by non-linear variable relationships. The most frequently used state of these relationships corresponds to a two-degree polynomial. Thus, to express the response surface using a two-degree polynomial, we must have an experimental plan which considers one factor and a minimum of three different values. A complete factorial 3 experiment requires a great number of experiments (N = 3 k = 3 N = 27 k = 4 N = 81). It is obvious that the reduction of the number of experiments is a major need here. We can consequently reduce the number of experiments if we accept the use of a composition plan (sequential... 

The fundamental level of the factors and their variation intervals have been established and are given in Table 5.26. We accept that the factors domains cover the great curvature of the response surface. Consequently, a regression relationship with interaction effects is a priori acknowledged. 

Figure 5.9 (a) Response surface for k = 2. (b) Sections of the response surface and ofthe gradual displacement towards the domain of the great surface curvature. 

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