# Smart Product Design Process through the Implementation of a Fuzzy Kano-AHP-DEMATEL-QFD Approach
## Literature Review
### Decision-Making Trial and Evaluation Laboratory (DEMATEL)  
DEMATEL method was originally developed by the Science and Human Affairs Program of the Battelle Memorial Institute of Geneva. It was intended to study and resolve the complicated and intertwined problem group [18; 23; 47]. Unlike the traditional techniques, such as AHP with the assumption that elements are independent, DEMATEL method uses the structural modeling technique to identify the interdependence among the elements of a system through a causal diagram using digraphs to portray the basic concept of contextual relationships and the strengths of influence among the elements [48; 49].  
DEMATEL has the following advantages:  
* It effectively analyzes the mutual influences (both direct and indirect effects) among different factors and understands the complicated cause and effect of relationships in the decision-making problem [14].  
* It can visualize the interrelationships between factors and enable the decision-maker to clearly understand which factors have mutual influences on one another. The DEMATEL can be used not only to determine the ranking of alternatives but also to find out critical evaluation criteria and measure the weights of evaluation criteria [14].
* Although the AHP can be applied to rank alternatives and determine criteria weights, it assumes that the criteria are independent and fails to consider their interactions and dependencies. The Analytic Network Process (ANP), an advanced version of the AHP, can deal with the dependence and feedback between criteria; but the assumption of equal weight for each cluster to obtain a weighted supermatrix in the ANP is not reasonable in practical situations [14].  
On the other hand, in comparison to other MCDM methods, the possible disadvantages of the DEMATEL technique may be the following:  
* It determines the ranking of alternatives based on interdependent relationships, but other criteria are not incorporated in the decision-making problem [14].
* The relative weights of experts are not considered in aggregating personal judgments of experts into group assessments [14].
* It cannot take into account the aspiration level of alternatives as in the Vlse Kriterijumska Optimizacija Kompromisno Resenje (VIKOR) method or obtain partial ranking orders of alternatives as in the Elimination et Choix Traduisant la Realite (ELECTRE) approach [14].  
Therefore, DEMATEL has been integrated with other MCDM methods (i.e., QFD) to combine their desired properties [18; 50]. On a different note, DEMATEL has been applied for underpinning a wide range of decisions. Indeed, the literature reports several DEMATEL applications like identifying customer preference factors when buying a particular good [51], identifying the best improvement action in a quality management system [52], assessing and selecting different strategic decisions [53], supplier selection [54; 50], and others. DEMATEL has been also used to pinpoint drivers for ICT [55] and create an evaluation system for healthcare management [56]. Additionally, DEMATEL has been also integrated into QFD to find the relationship among different customer needs [57].  
Table 1 depicts relevant related researches integrating different techniques. From that table, it could be observed that the proposed approach differed from others found in the literature. Specifically, although there are many models related to the design process, many of them fail in translating words into requirements and actions effectively. Additionally, many of them do not consider the fuzzy nature of human judgments, the interrelations among criteria, and the use of satisfaction indexes. The proposed model included all these features, as detailed in the following description:  
* Adequate relative importance (weight) of customer requirements with the implementation of AHP.
* Real impact estimation of customer requirements (fuzzy Kano)
* The dependence relationship between design actions (DEMATEL)
* The relation between design action and customer needs (QFD)