Keywords: survey, social media, data donation, accuracy

Digital, and within that, social media use is increasingly being treated as a significant predictor or outcome variable for various topics and research questions. The validity of these approaches, however, lies in the validity of media use measures. This study extends the current body of literature by contrasting survey reports of Facebook use utilizing digital data donated. Our main research question is: Do self-reports of Facebook use correlate with actual behaviour found in the digital data? Furthermore, in a pre-registered experiment, we varied the ordering of the survey items to assess which item order yields more accurate responses. Data comes from a data donation study, fielded in Hungary, between February and June 2023. Respondents were asked to participate in the project in three ways: answer a short questionnaire with eligibility questions and a consent form (1), download and upload their social media data to the project's website (2), and answer a 30-minute-long survey. We used a standard self-reported measure of Facebook activity and contrasted it with frequencies derived from donated Facebook data. In the experiment, one group received questions in an order such that the frequency of each activity was first asked about their activity in general followed by items on specific topics, whilst the other group received the same questions in a specific-general order. The preliminary results show a relatively strong correlation between survey reports and digital measures, but self-reports tend to overestimate less frequent activities and underestimate more frequent activities. For some measures, the general to specific question order design seems to work better. This study helps to understand to what extent self-reported social media use measures provide accurate behaviour estimates. We further shed light on the role of questions order and make recommendations for survey design.