## 4 Methodology  
### Questionnaire Design  
This study adopted quantitative research methods and collected data through questionnaires for testing theoretical models. The questionnaire survey method was chosen based on three considerations. First, the study needs to obtain subjective perception data from university students regarding their online consumption experience assisted by LLMs. This psychological measurement indicator is suitable for assessment through standardized questionnaires. Secondly, this survey method can enhance the meaning of the research results [67]. Finally, this study focuses on perceived data, and these data are not available from any public source, resulting in the need to obtain them through original data collection. The questionnaire is grounded in the existing literature, systematically organizing measurement items related to relevant constructs (Table 1). It adjusts existing established scales based on the research subjects and context of this study, forming an initial measurement tool for assessing university students' perceptions and willingness to continue using LLMs to assist with online consumption. The survey questionnaire is composed of threesections. The initial segment of the study encompasses an informed consent form and confirmation that all respondents have attained a minimum age of 18 years and have utilized LLM-related technology to facilitate online purchases of sustainable products a minimum of three times within the past three months. In the event that the subjects do not consent to the collection of their anonymous data for the purposes of this study, or in the event that they do not meet the established requirements, they will be excluded from the survey. The second part of the survey collects demographic information about the respondents. The third part of the study involves the collection of data concerning the respondents' user experience. The assessment of all items in this section is conducted using a Likert scale, ranging from 1, indicating \"Strongly Disagree,\" to 5, indicating \"Strongly Agree.\"  
This study implemented a rigorous questionnaire localization process to ensure cross-cultural validity. The questionnaire was translated using a back-translation method. First, a researcher who is not a native English speaker translated the content into another language. And then, another researcher independently back-translated it into English. The two versions were then compared to ensure semantic consistency. In the end, three equivalent versions of the questionnaire were produced in English, Chinese, and Korean. In addition, we invited three experts in computer technology and three experts in marketing research to form a review panel. This panel conducted multiple preliminary tests on the questionnaire items and optimized the clarity of the wording based on professional advice. The original translation team then checked the revised questionnaire and completed the final version. The results of the pre-test conducted on 30 participants with experience using LLMs to assist with online consumption of sustainable products confirmed that the entire development process ensured that the measurement tools met the research requirements. To ensure the diversity and representativeness of the sample, researchers distributed the questionnaire via various channels during the data collection process. These channels included relevant sections of mainstream social media platforms, sustainable product purchasing community forums, and related interest groups. Furthermore, measures were implemented to improve data quality. Firstly, the concept of LLMs was clearly defined in the introductory section of the questionnaire, with a specific mention that ChatGPT is a typical application of this technology [74]. Secondly, a demonstration video was attached to visually showcase the specific application scenarios of ChatGPT (for example, ChatGPT 4o)