**4. Evidence-Based Practice — EBP**

The term evidence-based used as a prefix and a denominator of interventions and methods comes from medicine. The term evidence based means that the choices of interventions and as‐ sessments are based on a research literature not simply professional experience or previous practice. Evidence-based practice has been important within the area of early communication intervention. The behavioural intervention tradition with its roots in the research clinic has pro‐ duced a lot of high-quality research during the years. Other types of interventions has been less researched and sometimes have used methods and produced data that are different so that com‐ parisons of effects are hard or impossible to do. This has also led to an interesting discussion of how to do EPB within the field of communication intervention. Ralph W. Schlosser, professor at NorthEastern University, USA, has been of great importance in this respect. Partly because he is spreading knowledge about evidence-based practise (EBP) and due to the many thorough com‐ pilations of research that he has done, but also in demonstrating the problems and shortcom‐ ings using EBP in relation to the field of augmentative communication intervention [49]. One of these problems concerns the use of the Randomized Controlled Trial or Study (RCT) as the gold‐ en standard, as RCTs are almost non-existent within the AAC field. There are many reasons to this but the main ones are that (1) children with communicative disabilities are so heterogene‐ ous and (2) that randomization is extremely difficult to put through due to ethical reasons. Schlosser has therefore suggested an alternative evidence hierarchy placing the meta-analysis on top [49, 50]. Schlosser and several other prominent authors within the field of communica‐ tion intervention research designs recommend the use of well-controlled single-subject re‐ search designs that can form the base for systematic meta-analyses.
