Modified quadratic loss function for a trivariate response with the exact feasible region for parameters

Abstract

This paper deals with modification of Taguchi's quadratic quality loss function (QQLF) for a trivariate responses, each having a NtB (nominal-the-best) type quality characteristic and correlated in pairs. It tends to improve and extend results obtained in [4,6]. Impossibility to solve nonlinear constraint in [6] resulted in an approximate algorithm to determine unknown parameters of QQLF. Here the nonlinear constraint is solved analytically and consequently the exact feasible region is obtained. The QQLF is formed by means of the parameters from the restrictive feasible region and proved suitable for all the types of correlation among quality characteristics.