Doing longitudinal interpretative phenomenological analysis: a conceptual overview and practical guide

Longitudinal qualitative research explores time by analyzing data gathered during an extended period to understand how processes and experiences evolve. Interpretative Phenomenological Analysis (IPA), with its focus on lived experience and sensemaking is particularly adaptable to longitudinal designs and studying temporality. This article provides a conceptual overview and practical guidelines for the analysis phase of a longitudinal IPA (LIPA) study.The proposed approach includes inductively analyzing data for each participant at each timepoint to generate Personal Experiential Themes (PETs). These are subsequently compared across time to define Longitudinal PETs (LPETs) which are then synthesised across participants to identify Longitudinal Group Experiential Themes. Through a worked example, idiography is highlighted as key to capturing individual trajectories and the continuous reinterpretation of past, present, and future. We discuss analytic considerations- including explicit and implicit change, iterative interpretation, and the balance of inductive and abductive reasoning - providing systematic guidance for future LIPA research.