  The wide adoption of mobile devices and social media platforms have
dramatically increased the collection and sharing of personal information. More
and more frequently, users are called to take decisions concerning the
disclosure of their personal information. In this study, we investigate the
factors affecting users' choices toward the disclosure of their personal data,
including not only their demographic and self-reported individual
characteristics, but also their social interactions and their mobility patterns
inferred from months of mobile phone data activity. We report the findings of a
field-study conducted with a community of 63 subjects provided with (i) a
smart-phone and (ii) a Personal Data Store (PDS) enabling them to control the
disclosure of their data. We monitor the sharing behavior of our participants
through the PDS, and evaluate the contribution of different factors affecting
their disclosing choices of location and social interaction data. Our analysis
shows that social interaction inferred by mobile phones is an important factor
revealing willingness to share, regardless of the data type. In addition, we
provide further insights on the individual traits relevant to the prediction of
sharing behavior.
