Abstract: A lot of research into the use of recorded lectures has been done by using surveys or interviews. We will show that triangulation of multiple data sources is needed. We will discuss how students use recorded lectures according to their self-report and what actual usage of the recorded lectures can be derived from the data on the system. We will present the data collections and cover areas where the data can be triangulated to increase the credibility of the results or to question the students' responses. The triangulation shows that we lack data for a number of areas. We will need high-quality surveys and interviews combined with the log data to get a complete picture. We need to be able to link data sets together based on the identification of the individual students, which might raise privacy issues.