Abstract: Best Practices in Longitudinal Research This workshop will identify best practices for longitudinal research through an in-depth exploration of methods and metrics for collecting and analyzing user data over time. This is the fourth event in an ongoing effort by the organizers to enhance our current body of knowledge about longitudinal research. Keywords Longitudinal data, longitudinal research, comparative analysis, user research, study design ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous.