Do consumers know what they want?

Predicting one’s own decision‐making policies is evidently a useful skill. How good are consumers at it? In spite of its importance, the question has not been much studied directly, although hints can be found in several parts of the literature. This article describes an experiment that identifies how much knowledge consumers have about an important purchase: a mobile phone. A total of 94 consumers provided ratings of the importance of six attributes and preference for several choices of mobile phone plans that were advertised in the market. Consumers’ self‐knowledge was assessed by three methods: comparing the product attribute importance derived from the subject’s model with the attribute importance derived from a conjoint analysis model; comparison of predicted judgments generated by the subject’s model with their holistic judgments; and comparison of the actual purchase of a mobile phone with the prediction generated by the subject’s model. Results show that consumers have a relatively good predictive power of a product they have chosen. However, this knowledge is not perfect. The results have important implications for companies that collect information about preferences from consumers.