“…Some of the authors in this field advocated the use of fuzzy set theory (Delgado, Molina, Sánchez, Ariza, & Vila, 2004;Fasel & Zumstein, 2009;Laurent, 2002) or rough set theory (Naouali & Missaoui, 2005, 2006 to handle the data incompleteness and imprecision. The first ones proposed fuzzy multidimensional database models and fuzzy slices, dices and aggregations while (Naouali & Missaoui, 2005, 2006 contributions involve data approximation techniques by means of rough sets (upper and lower approximations). Also, the authors Pitarch, Favre, Laurent, and Poncelet (2012) exploited the fuzzy logic in proposing new contextual hierarchies to allow the consideration of data experts knowledge for the definition of the hierarchies.…”