# What Went Wrong? Predictors of Contact Tracing Adoption in Italy during COVID-19 Pandemic
## 1 Introduction
### Hypothesis Development  
Based on the aforementioned theoretical models and research evidence, we developed six hypotheses. Some literature shows that sociodemographic variables such as gender, education level, and income have no influence [27; 43], or marginal influence in the case of age [43], on the download and use of contact tracing apps. Other works showed precisely the opposite regarding the role of age in determining app usage. Indeed, old people are generally less likely to have smartphones, are less tech-savvy, and are less inclined to install and use new applications on their smartphones [44; 45; 46]. Nevertheless, in our case, since we were interested in why people that are, in theory, able to adopt such systems (i.e., they have both the opportunity and skill to use CTs) did not use them, we recruited participants that were plausibly quite familiar with new technologies, regardless of their age. For this reason, we expected age to not be related to CT adoption. **Hypotheses 1 (H1)**. _Sociodemographic variables such as age, gender, education level, and income do not influence the download and use of the Immuni application_. Literature shows that people who have a higher perception of the efficacy of contact tracing systems as a way to fight the pandemic will download and use contact tracing apps more often [27]. Following these results, for the second hypothesis of our study, we expect that people who have a higher perception of Immuni-related efficacy will download and use it more often. The study of [PERSON] et al. [27] identified performance expectancy as a core predictor of COVID-19 adoption. Performance expectancy was defined as the advantages that users expect from using technology. Thus, the authors predicted that people who have positive expectations concerning the app's performance in dealing with the COVID-19 pandemic would be more inclined to adopt and use the app. **Hypotheses 2 (H2). **_People who score a higher Immuni perception of efficacy have a higher probability of downloading and using it._  
Social influence refers to individuals' beliefs that important others think they should be using the technology. Social influence has been found to be important in the early stages of an individuals' experience with a new technology fostering its adoption [27]. Therefore, as we investigated a new technology, such as contact tracing systems, we expect that if individuals know that significant others use the CT app, they will be more likely to do it themselves [27]. **Hypotheses 3 (H3). **_Individuals who know important others who have downloaded and installed the Immuni application have a higher probability of downloading and using it._  
According to the literature, peoples' beliefs of the gravity of the COVID-19 pandemic and their perceived vulnerability did not predict the intention to adopt CTs [27]. Apparently, COVID-19 concerns were negatively associated with the intention to download contact tracing apps, while they appeared to increase social conservatism levels and privacy concerns [47]. Fear of COVID-19 instead seemed to affect the acceptance of mobile applications to deal with the COVID-19 pandemic [43]. **Hypotheses 4 (H4). **_People who score a higher likelihood of infection (or risk perception) will download and use the Immuni application more._  
Attitude towards technology is related to acceptance of contact tracing apps [43]. [PERSON] et al. [27] linked innovativeness to the desire to look for and try out new things (e.g., ideas, services, products). For this reason, we expected that a positive attitude toward technologies would favor people's adoption of CTs. **Hypotheses 5 (H5). **_People's attitudes towards the Immuni application influence the download and use of it._  
Psychological models show that the acceptance of a certain message depends on the judgment of the source in terms of trust, competence, and credibility [37; 38; 39]. Thus, a credible and trustworthy source had a higher probability of persuading the receiver of the message [40].