**4. Method**

*4.1. Questionnaire Design and Survey*

The scales for all the variables in the study were designed based on those that have been validated by existing studies. The scales used to measure the variables in the NAM were adapted from a related study conducted on the basis of the NAM (Sang, Yao, Zhang, Wang, Wang, and Liu [36], Kim, Woo, and Nam [38], and He and Zhan [34]). The scale for measuring overuse was adapted from Lee, Kim, Fava, Mischoulon, Park, Shim, Lee, Lee, and Jeon [28]; the scale for measuring the inconvenience to life was adapted from Lee, Kim, Fava, Mischoulon, Park, Shim, Lee, Lee, and Jeon [28]. After the initial questionnaire design was completed, we asked experts in the field to review and revise it and conducted a smallscale pre-test to improve it. Please refer to Appendix A for specific measurement items.

Some of the other design parameters of the scale are as follows. (1) The scale uses a 5-point Likert scale. (2) The questionnaire questions are in English, while the survey was conducted in China; thus, we invited two linguists who were proficient in English to translate the questionnaire from English into Chinese to ensure that the Chinese presentation was error free and easy to understand. (3) We designed reverse questions in the questionnaire to detect invalid questionnaires. (4) Our questionnaire was designed as an anonymous survey, where participants were informed of the purpose of the study, only the necessary data were collected and kept strictly confidential, and respondents were given gifts to participate. (5) In accordance with the regulations of the Research Ethics Committee of Yeungnam University (https://irb.yu.ac.kr/02\_gid/gid01.html, accessed on 20 June 2022), no specific ethical review was required for the questionnaire survey of this study.

We selected people living in Shanghai as the population for this study. First, Shanghai is a mega-city in China with a large population, a developed economy, and a rapid diffusion of new technologies and policies; the use of a DCTA to enhance health verification and entrance registration is an important initiative to strengthen COVID-19 prevention in Shanghai. Second, Shanghai had a massive COVID-19 outbreak in March, and after the pandemic was brought under control, the full deployment of "place code" and "health verification machine" devices was quickly made mandatory for citizens to use, while citizens had to scan the QR codes on these devices through their cell phones to complete health verification and tracking registration before entering places (see Figure 3) [52].

**Figure 3.** Tracking display/registration QR code generated by the DCTA in Shanghai.

In this study, we randomly joined some instant messaging software chat groups in the Shanghai area and randomly conducted questionnaires among members of them. Participants who completed the survey would receive a CNY 10 shopping coupon. In total, 400 respondents living in Shanghai were randomly surveyed through various SNS platforms from 1 July 2022 to 10 July 2022. Finally, we received a total of 379 questionnaires and obtained 313 valid questionnaires (82.5%) by removing duplicate responses, biased reverse questions, and those with less than 2 min of answer time.
