## 2 Materials and Methods
### Research Methodology  
Taking into consideration the aforementioned research questions, our exploratory research aims at investigating University of the Aegean students' perceptions regarding their BS acceptance. Constructs and significant factors from the above-mentioned technology acceptance models are adopted that being utilized in previous research for biometric systems acceptance, so as to design a more inclusive research instrument for students' BS acceptance in HEIs in Greece. The items were based on measures derived from [3; 4; 12; 30; 41]. These are knowledge, adoption, usability, reliability, intention to use biometric systems, privacy and security concerns, confidence and social control, as well as specific demographics and social attributes of the users. Figure 1 represents the research methodology flow chart. This survey is based on the undergraduate, postgraduate and doctoral students of the eighteen departments of the University of the Aegean. In order to have access to a large part of the research population for the results to be able to be generalized [42], a quantitative approach was selected, and a structured questionnaire was developed. All items regarding students' perceptions for BS acceptance and usage were compiled from  
Figure 1: Research methodology flow chart for students’ BS acceptance in Greek HEIs. previous literature, presented in Section 2. In this respect, the anonymous instrument (Appendix A) is divided into 7 sections according to the constructs that were adopted to our research design, namely knowledge, adoption, usability, reliability, intention to use BS, privacy and security concerns and confidence and social control concerns, including 38 items. The closed-ended type items are divided into: (a) dichotomy questions, allowing the respondents to choose between two answers (Yes/No); (b) Likert-scale questions (from 1 to 5) and (c) multiple choice questions. Its reliability and validity were tested in a pilot survey addressed to 150 students, preceding the main sampling, and after the instrument being revised accordingly, it received its final form. The Kuder-Richardson reliability coefficients (KR-20) index was applied to calculate the reliability for the dichotomy-type queries, while Cronbach A type was used for Likert-scale queries. Finally, a set of nine items to address the participants' socio-demographics was included. Age groups were divided, considering that in the University of the Aegean, most of the undergraduate students belong to ages 18-21 during the four-year bachelor degrees and to 18-22 during the five year ones; most of the postgraduate students belong to the 21-35 age group; most of the PhD candidates in 31-45; and a percentage of students within all cycles of studies concerns the 46-60 age group. Besides the variables that are usually adopted (gender, age, etc. ), since our survey design is a descriptive one aiming at obtaining as much information as possible in order to identify which are the critical factors and guide future work, the variables of the study of level and parents' occupation were included. In particular, the father's and mother's occupations were asked, accordingly to Ref. [43] theory, since social background impacts individuals' practices and cultural issues. Family is one of the most important socialization agents, enhancing values which are more practical than theoretical. Parents determine all family members' attitudes toward several life domains, as well as determining factors for information technologies acceptance and adoption [44]. Due to the influential role that parents play, which in Greece is even more observed, we believe that it is essential to identify if the parents' occupation, as an acknowledged important variable in other domains, affects students' willingness to accept and use BS. The identification of these factors may have the potential to further our understanding of students' BS acceptance and could inform the development of new approaches to increase their engagement and inform future policy.