Many communication disorders are poorly understood and many treatments used in therapy remain unproven. Speech and Language therapists are increasingly involved in research in these areas but may lack the training and experience required to conduct it. Not the least of their problems is that few textbooks discuss the specific problems of research design in communication disorders. ''Research Methods in Speech and Language Therapy'' fills this gap. It will serve as an introductory text for students who are training to be therapists and as an introduction to more advanced methods for clinicians involved in research. Different approaches to research are described and the basic principles of research design and statistical analysis described. The book uses a wide range of published research to illustrate how research may be conducted in these areas and gives particular attention to the problems of researching the effectiveness of therapy.