Welcome to the final part of the series ‘Understanding research’. To date, we have focused on terminology, qualitative methods, quantitative methods and the randomised control trial (RCT) (Gethin, 2008, 2009a, b; Gethin and Clune-Mulvaney, 2009). It is appropriate therefore to finalise the series by discussing studies which use a mixed methodological approach in which quantitative and qualitative designs are combined to obtain a deeper understanding of the research problem.