"If You Put All The Pieces Together...": Attitudes Towards Data Combination and Sharing Across Services and Companies

Online services often rely on processing users' data, which can be either provided directly by the users or combined from other services. Although users are aware of the latter, it is unclear whether they are comfortable with such data combination, whether they view it as beneficial for them, or the extent to which they believe that their privacy is exposed. Through an online survey (N=918) and follow-up interviews (N=14), we show that (1) comfort is highly dependent on the type of data, type of service and on the existence of a direct relationship with a company, (2) users have a highly different opinion about the presence of benefits for them, irrespectively of the context, and (3) users perceive the combination of online data as more identifying than data related to offline and physical behavior (such as location). Finally, we discuss several strategies for companies to improve upon these issues.