Nested incomplete block designs in sensory testing: construction strategies

In most cases the choice of sensory designs is driven solely by the limitation of assessor fatigue. However, often there is an additional but unrelated kitchen constraint, which limits the number of products that can be prepared for a given session. Nested incomplete block designs provide the opportunity to take proper account of both of these constraints, and in so doing, identify opportunities for more effective product comparisons. Here we describe a new three-stage method for constructing such designs and identify criteria for assessing their quality. We illustrate an extension of the method for situations where there is a factorial product structure and some contrasts are judged more important than others. (C) 2001 Elsevier Science Ltd. All rights reserved.