a for senior leaders, the Think Family Education (TFE) app developed for schools, as well as targeted risk models (CCE / CSE and NEET models) that are embedded in the TFD and (NEET model only) the TFE. This process also yielded the following theory of change in simplified form, which Social Finance, as the evaluator, has iterated slightly since its original formulation, as more has been learned about the TFD and the services it supports. Social Finance Limited +44 (0) 20 7770 6836 87 Vauxhall Walk, London SE11 5HJ socialfinance.org.uk 21 Figure 10: Clarified Theory of Change 4.3 Testing the Theory of Change To test this model, we adopted a mixed methods research approach, combining primary qualitative and quantitative data collection methods. Doing so allowed us to understand the first-hand experiences of those who designed, built and implemented the TFD, those who use it and associated products, as well as making use of statistical information about actual TFD usage and other operational data. For clarity, in respect of TFD users, we have segmented teams into four categories of practitioners in Childrens Services, rather than naming specific teams. These map broadly to the different use cases that were established through the TFD’s development. The use cases are: Triage practitioners; Early Intervention practitioners; Social Care practitioners; and practitioners from other teams or directorates, e.g. housing or education. Qualitative methods Between April and November 2023, we conducted 36 in-depth interviews with practitioners, managers, developers, and information governance specialists in Bristol City Council. We also carried out a 2-day participant observation session on-site at Bristol City Council offices. This consisted of multiple sessions shadowing team meetin