Longitudinal studies track the same individuals over long periods, often years or decades, using continuous or repeated measurements. These studies are typically observational, collecting both quantitative and qualitative data on various exposures and outcomes without applying any external influence (Caruana et al 2015).
Follows individuals over time starting at the present. Baseline data is collected on enrollment before outcomes develop. and then data is collected as the characteristics or circumstances of the participants changes.
Looks back at data from past records to study outcomes that have already occurred. Information is collected about participants past experiences and exposures and where some may have already developed the outcomes of interest
Chela-Alvarez, X., Leiva, A., Gallardo-Alfaro, L., Bulilete, O., Vidal-Thomas, M., & Llobera, J. (2022). Anxiety, depression, and concern about employment status of hotel housekeepers in the balearic islands during the COVID-19 pandemic: a longitudinal study. Frontiers in psychology, 13, 842335. Full Text