Nested incomplete block designs in sensory testing: construction strategies

In most cases the choice of sensory designs is driven solely by the limitat ion of assessor fatigue. However, often there is an additional but unrelate d kitchen constraint, which limits the number of products that can be prepa red for a given session. Nested incomplete block designs provide the opport unity to take proper account of both of these constraints, and in so doing, identify opportunities for more effective product comparisons. Here we des cribe a new three-stage method for constructing such designs and identify c riteria for assessing their quality. We illustrate an extension of the meth od for situations where there is a factorial product structure and some con trasts are judged more important than others. (C) 2001 Elsevier Science Ltd . All rights reserved.