Number of consumers necessary for sensory acceptability tests

Basic concepts necessary to estimate the number of consumers necessary for sensory acceptability studies (N), variability data on previous consumer studies and estimations of N for different values of Type I and Type II errors are presented. The standard error of the experiment, reported as the root mean square error from the analysis of variance, was similar over 108 reported studies conducted in five countries over a wide range of food products. This allowed estimating the number of consumers necessary for future studies. These estimations are presented in a table. Considering the average standard error, an alpha value (Type I error) of 5%, a beta value (Type II error) of 10% and a difference between sample means of 10% of the sensory scale, gave an N value of 112 consumers for this particular set of parameters.