  This workshop paper reports on an ongoing mixed-methods study on the two
arguably most popular social network sites, Facebook and Twitter, for the same
users. The overarching goal of the study is to shed light into the nuances of
social media selection and cross-platform use by combining survey data about
participants' motivations with usage data collected via API extraction. We
describe the set-up of the study and focus our discussion on the challenges and
insights relating to participant recruiting and data collection, handling and
dimensionalizing usage data, and comparing usage data across sites.
