Moving from randomized controlled trials to mixed methods intervention evaluations

This chapter explores why mixed methods intervention evaluations are needed when undertaking randomized controlled trials in order to address a wide range of questions relevant to understanding the effectiveness of an intervention. It describes three frameworks that illustrate different ways in which mixed methods intervention evaluations may be undertaken within the context of a randomized controlled trial: the temporal framework; the process-outcome framework, which includes process evaluations; and the “aspects of a trial” framework. The chapter considers how the language used to describe qualitative research undertaken with trials can represent different underlying assumptions about the relative value of the qualitative research in relation to the trial. The chapter concludes with a discussion of some of the challenges that arise when undertaking mixed method intervention evaluations and the value of including qualitative research in systematic reviews of trials via evidence synthesis.