optimizations, the response optimizer was carried
out by using the Minitab software for determining
the exact optimum level of independent variables
leading to individual and overall response goals.
Response optimizer allows us to compromise a
single response or a set of responses. This
numerical response optimization allows us to
interactively change the input variable settings to
perform sensitive analyses and possibly improve
the initial solution 24.
Verification of models: Both practical and
theoretical methods can be applied for validation.
For practical method, the experimental data were
run again by using optimum point obtained by
each factor. The model is validated practically if
obtained data are close to predicted data. For
theoretical method, the experimental data were
compared with predicted values in order to verify
the adequacy of final reduced models by using 2-
sample t-test. Close agreement and no significant
difference must exist between the experimental data and predicted
values 24.