Modelling and monitoring the decision process of wine tasting panellists

This paper presents a method for modelling and monitoring the individual decision process of wine tasting panellists. The individual decision of approving or rejecting a wine is based on the panellist’s evaluation of the wine characteristics. The decision process is modelled through a logistic regression where the dependent variable is the decision itself (rejected–0 or approved–1) and the independent variables are the characteristics that were considered relevant for the wine evaluation. The process is monitored using a CUSUM control chart for binomial proportions. The control chart variable is the number of disagreements observed (in a sample of size N) between the actual decisions of the panellist and the results anticipated by the logistic regression model. The method was tested in the Port Wine Institute. Such a test revealed that the logistic model is a useful tool for clarifying both the way in which the wine evaluation process is carried out, and how the decisions are taken. Furthermore, the test has also showed that the control chart is responsive to significant changes of the individual decision process.