The Feasible Domain
The Feasible Domain is the Key Concept Behind the Expeka Method.
The feasible domain is defined by a volume in the multidimensional factor space of the process, which best discriminates between “accepted” tests inside and “rejected” tests outside.
A test is declared “accepted” if the properties of the process output are within the necessary specifications.
This volume is fitted by a multidimensional ellipsoid which is sculptured by the lower and upper limits of the factors.
The Figure below displays a sketch of the feasible domain.
The polygon corresponds to the trace of the experimental domain that is defined by the lower and upper limits of the factors.
Tests corresponding to dots have been “accepted” and are located inside the multidimensional ellipsoid.
Tests corresponding to Xs have been “rejected” and are located outside the multidimensional ellipsoid.