## 2 Materials and Methods
### Survey Design and Data Collection  
A survey is a systematic method for gathering information. Surveys are conducted to collect information that reflects the attitudes, behaviors, opinions, and beliefs of the population that cannot be observed directly. Therefore, the survey questions must address our research question. The success of research using a survey depends on how closely the answers people provide to survey questions match how they think and really act. This methodological approach allows us to obtain a precise and contextualized representation of reality within the population sample. Thus, the survey design [28; 29] plays a crucial role in our research, as it serves as a foundation to support the reference values used in the decision matrix being developed. It was decided to design the survey using a Likert scale as it allows to know the opinion of the individuals surveyed through a questionnaire containing specific, multiple-choice questions that facilitate data measurement and are easy to interpret using statistical methods [32]. This tool indicates the degree of satisfaction or agreement with the statements given on a scale composed, in our case, of five levels. Due to the type of data to be collected, the survey was sent to competent municipal technicians who know the waste management systems in the cities and to users of these systems. The survey was divided into three blocks. The first section of the survey comprises eight general questions designed to gather information about the participant's profile and secondly to gauge their familiarity with pneumatic solid urban waste collection systems. This section includes questions on the participant's sex, age, level of education, mobility impairment status, municipality, and job title. This section serves a dual purpose: first, to collect demographic data, providing essential context for analyzing the survey data in relation to the study variables; second, to filter out participants who lack knowledge about pneumatic collection systems. If a respondent indicates unfamiliarity with these systems, the survey is discontinued for them. Conversely, if the respondent is acquainted with these systems, the subsequent sections aim to assess their satisfaction levels with the pneumatic collection systems implemented in their municipality. The purpose of the second block of the survey is to assess the significance attributed by the respondents to each one of the variables under study. Therefore, this section contains specific questions related to each variable listed in Table 2, which details the correlation between study variables and survey questions, ensuring alignment with the selection matrix. In Table 3, the questions posed in the survey are listed, where a Likert scale has been used. Respondents are asked to consider the degree of importance or satisfaction for each variable, with 1 meaning \"not at all important\", \"very dissatisfied\", or \"nothing\" and 5 meaning \"very important\", \"very satisfied\", or \"excellent\". After each question, respondents have the opportunity to write comments to provide additional context or details regarding their ratings. The third block of the survey focuses on the interviewee's perspectives and preferences regarding pneumatic collection systems for solid urban waste. It includes questions aimed at understanding whether respondents would support exploring the implementation of pneumatic systems in municipalities that currently lack them, or if this issue is not a priority for them. Additionally, the block examines the interviewee's preference between pneumatic and traditional solid waste collection systems if they were to change their residence. It also seeks to determine which waste collection system--either a five-fraction system (packaging, paper, glass, organic, and rest) or a two-fraction system (wet for organic waste and dry