## 4 Research Methodology
### Sample and Data Collection  
In this study, the necessary data on user attitudes were determined by surveying in the period from January 2024 to May 2024 using an online questionnaire. To obtain a representative sample, an online questionnaire was sent to individual companies and faculties, students, and pensioners, as well as users of social networks in Belgrade, observing the residents of Belgrade as the target group. Bearing in mind that the biggest problem of traffic congestion and environmental pollution is in the central city zone, the research area included the target narrower central zone, including other populated areas of Belgrade within a radius of 15 km from the center. The given area was considered with the aim of examining attitudes and encouraging users to switch to the use of environmentally friendly and sustainable electric bicycles. After incomplete questionnaires with illogical answers were removed from the total sample of 703 respondents, the valid sample used in further analysis consisted of 680 respondents. However, since users who do not currently use e-bikes during their movements were important for creating the model and for further analysis, the valid sample used for the study of the acceptability of these vehicles was 626. Illogicality was determined by control questions.  
To obtain the most authoritative results of the research, the answers of the respondents who had the opportunity to see and face the problems of traffic congestion and environmental pollution in the territory of the city of Belgrade were important. During the research, the respondents were not presented with any additional information regarding the problem of environmental pollution. In this regard, the respondents gave answers to the questions only based on their perceptions of the environmental problems of road vehicles in the territory of Belgrade.  
At the very beginning of the questionnaire, the respondents were highlighted the legal regulations, then the characteristics, advantages, and possible disadvantages of using electric bicycles. The given information was intended to present this mode of transportation as a possible solution to traffic congestion and the problem of environmental pollution in the territory of Belgrade. The questionnaire combined questions about Revealed preference, about the actual behavior of users when moving, and questions about Stated preference in order to analyze user preferences regarding the use of electric bicycles. The questionnaire was divided into four parts. The first part contained questions about the socio-demographic and economic characteristics of users, while the second part focused on trip characteristics. The third part was concerned with examining users' attitudes regarding environmental pollution, while the fourth aimed to determine users' attitudes regarding the use of electric bicycles, taking into account both respondents who use and respondents who do not use this mode of transportation. Finally, the respondents were asked about the reasons why they use/do not use electric bicycles and whether, in the end, solving the problem mentioned by the reason, they would still accept to use of an e-bike for the sake of reducing traffic congestion and environmental pollution. All questions in the questionnaire were closed. A five-point scale was used for certain questions.