Use of single case study research in child speech, language and communication interventions

Evidencing the effectiveness of speech, language and communication interventions continues to be a challenge for both researchers and practitioners who work with children and young people with speech, language and communication needs (SLCN). The use of case study design as a methodology for evaluating the effectiveness of these interventions, and the value of their contribution to the evidence base, is often not recognized. In this editorial, the merits of case study design as a robust and achievable methodology for practitioners to use to evidence the effectiveness of their interventions are discussed. Child Language Teaching and Therapy has published a number of case studies or case series reports over the years. Some case studies have been descriptive, with the aim of explicating aspects of a child’s difficulties. Carvey and Bernhardt (2009) used a framework for profiling intentional communication to describe the skills of a child with a rare genetic syndrome, thus adding to the literature on this particular disorder. Worth and Reynolds (2008) presented detailed assessment findings of a boy with Asperger’s syndrome and showed how these enabled a better understanding of the nature of his difficulties. The findings were explored in relation to the research literature and the implication for assessment practices and for intervention. Murphy and Dodd (2010) used assessment findings from the case of a child with a hearing impairment and a non-dominant language home background to discuss diagnostic criteria for specific language impairment. Whilst this type of case study is useful for illuminating our understanding of children with SLCN, it neither aims, nor is designed, to evaluate interventions. However, case study research that includes some element of experimental control can and does contribute to the evidence base for speech, language and communication interventions. Within a hierarchy of evidence composed of five levels, the highest is systematic reviews, and meta-analyses of randomized controlled trials, single case studies and case study series are ranked at level 2, above observation and expert opinion (Sackett et al., 2000). Logan et al. (2008) also present levels of evidence for single case research, from those that are designed to prove causal inference of the effects of intervention, to those that can hint at or suggest causal inference. These experimental case studies are known by a number of terms, such as single subject design, single subject research, single case design/research and n of 1. The design can include more than one individual receiving the same intervention reported as a case series or case study series. Each participant serves as his or her own control (Horner et al., 2005). Studies such as these have been and are published in Child Language Teaching and Therapy and can make an important contribution to the evidence base. 457766 CLT28310.1177/0265659012457766Child Language Teaching and TherapyEditorial 2012