## 4 Methodology  
The Delphi technique was used in this investigation. This technique is one of the research methods used for prospective investigation. Delphi is a prospective method that is considered suitable for analysing opinions made about any topic. These opinions must be made without any pressure or influence from the experts that make up the group. This method means that the results of any consensual study can be validated for the near future [41; 42]. The Delphi technique is flexible and uses consensual decision-making by experts for the subject under study. This technique uses a structured process to obtain information from a previously selected group of experts for a range of questions that are important for the subject under research. Self-administered individual questionnaires are presented using web tools and are added to by spontaneous opinions and anonymous comments that can be given at any time. Experts never exchange opinions with each other due to the risk that they may influence each other's responses. The Delphi technique systematizes a strategy for the analysis of opinions and comments that can be understood as a type of group interview that has some special characteristics [43]. The Delphi technique is a process that questions a group of specialists (carefully selected previously for their knowledge and professional experience) and uses the answers from successive questionnaires to find consensus of the answers given. The main objective of this methodology is to find a consensus of opinion for the ideas or aims that the investigation proposes [44]. It is interesting to note that the Delphi method, mainly due to the small number of participants--between 6 and 30--does not produce statistically significant results [45]. The different stages used in the method can be seen in Figure 1.  
First of all, the main research question must be stated. This is designed by a group of experts who are coordinated by the Delphi technique. A protocol must be established to ensure the correct evolution and development of the investigation. Once the main question has been correctly posed, the questionnaire prepared shown in Table 1 (in Appendix A), as Delphi Questionnaire 1 must be given to the selected experts. Once the results of this anonymous process are obtained, an in-depth analysis of the answers is carried out. To do this the group must be structured with the methodology protocol [48]. Then, once the answers to the first questionnaire have been analyzed, a report is made of any answers or opinions that differ from those given by the group. Once the discrepant answers have been analyzed, a second Delphi questionnaire is sent. In order to do this effectively, the conclusions of each round must be expressed clearly and concisely [49]. At this point the Delphi process is repeated again and the questionnaire is sent to the selected panel of experts and the answers are collected. These are analyzed and categorized in order to structure the discrepant responses or opinions about the proposed problems. Afterwards, the answers and the evolution of the comments made by the panel of experts are analyzed and a draft report of the conclusions of the study is prepared. Some authors suggest that this draft report should be given to the panel of experts to ensure that they confirm the results and conclusions of the process [48]. A final report is then prepared in which the evolution of each of the stages and questionnaires in the process are described [48]. In the event that any member of the panel of experts does not agree with something, the Delphi process should repeat the rounds of questionnaires until a consensus is reached. Figure 1: Diagram showing the stages in a Delphi study. (Based on [PERSON] and [PERSON], 2007; [PERSON] et al., 2019 [46; 47]. The profiles of each of the experts who participated in the Delphi process panel are presented below.