A comparison of methods for analyzing data from a three component mixture experiment in the presence of variation created by two process variables

The present paper is a study of the use of robust design methodology in a three-component mixture experiment containing two process variables. The mixture components are three wheat flours and the process variables are mixing time and proofing time of the dough. The main focus is on comparing three different techniques for analyzing the loaf volume, which is one of the key parameters of bread quality. The first technique considers the mean square error (MSE) computed across the levels of the process variables in the noise array, for each three component blend in the control array. The second method is based on analysis of variance (ANOVA) of the three factors, flour blend, mixing time and proofing time. The third method is a regression approach, where all factors (the three mixture components and two process variables) are modeled simultaneously. (C) 1998 Elsevier Science B.V. All rights reserved.