Research Article

A Confidence Region for Zero-Gradient Solutions for Robust Parameter Design Experiments

Table 2

The coverage rates for the GZG confidence region using the approximate and conservative critical values, and , respectively. The nominal coverage rate here is 95%. (Here no. of control factors, no. of noise variables, sample size, and residual df).

Model no. Approximate coverage ratesConservative coverage rates
Orthogonal designNonorthogonal designOrthogonal designNonorthogonal design

132402896.1%96.1%96.9%96.9%
242746096.3%96.3%98.0%98.0%
343725796.1%96.1%97.2%97.2%