Abstract:

This study contributes to the debate between the efficiency theory and the behavioural finance concerning investment strategies. It try to find an eventual complementarity between these two theories by modeling the decision making using the classical and the fuzzy logic. The sample is constituted by 25 firms quoted on Tunisian Stock Exchange. Daily data from January 2001 to December 2008 is used. The results chow that the fuzzy logic is better than the classical logic in explaining the complementarity between the efficiency theory and the behavioural finance concerning decision making.