Data Linkage (Skatova et al, 2019; blog). I work with Avon Longitudinal Study of Parents and Children (ALSPAC) and other Longitudinal Population Studies (LPS) to create a methodology for linking transaction data into LPS. Using qualitative and quantitative methods, I study a range of issues including participants’ attitudes to sharing transaction data with academic researchers, privacy-preserving, ethical approaches for data linkage, assessing the quality of linked datasets in terms of sampling and various biases, creating appropriate infrastructure for the linkages, creating routes for the linked data to be available for academic research via secure protocols.