A persistent dilemma in comparing
products is to know when the difference between them
becomes consumer relevant. Since the probability that
any two products are exactly the same is zero, rejecting
the null hypothesis that they are identical may not be
that informative; an analysis will always result in such
rejection provided there is a sufficient sample size.
What is more important to know is whether the products
differ by enough for their difference to be consumer
relevant - establishing this knowledge is an outstanding
problem in the sensory and consumer research fields and
various methods have been suggested. One method is to
benchmark product differences from past tests where it is
known that consumers continued to purchase the product
even in the presence of variability or change. This method
can be employed when products are routinely made in
different factories or when blend and flavor modifications
have already been introduced without any appreciable
loss of sales. Another approach is to link internal panel
measurements with consumer hedonic response to the set
of differences. But ideally, it would be useful to have a
consumer-based estimate of the average criterion that
consumers use to decide whether products are the same
or different. In this report we discuss a way of developing
this method through the use of same/different judgments.
This technical report appears as:
Rousseau, B. and Ennis, D. M. (2013). When Are Two Products Close Enough to be Equivalent? IFPress, 16(1) 3-4.
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This technical report also appears in our book, Tools and Applications of Sensory and Consumer Science.