What counts as evidence? Swimming against the tide: valuing both clinically informed experimentally controlled case series and randomized controlled trials in intervention research

Research into intervention with people with speech and language needs often takes the form of single-case/case series experimental studies (SCEDs) or randomized controlled trials (RCTs). This paper explores the nature of these designs, including their strengths/weaknesses and highlights the value of understanding the intervention outcomes for individual participants. An online survey gathered information on speech and language therapists’ views on their use of the different research designs. We conclude that both research designs are used to inform practice. SCEDs, in particular, are used in developing theories of intervention and informing therapy with individuals. Sound experimental intervention studies of both designs are needed.