Confidence intervals for the triangle test can give reassurance that products are similar

Abstract

One of the major advantages of the triangle test to set against its low statistical power is its potential for revealing discriminable sensory differences when the nature of the difference is unknown. That makes it an attractive tool for seeking assurance that there is no sensory difference between samples (after a process change, for instance). Mere absence of significant difference is completely inadequate to give that reassurance and power analysis is much better. However, power analysis requires three somewhat arbitrary parameter values to be selected in advance. An alternative approach based on exact binomial confidence intervals is described which needs only a single parameter, comparable to the alpha level in a test of significance, to be specified. It is shown that the amount of data usually envisaged for seeking reassurance about lack of difference is much too small to do the task adequately.