National Center for the
Dissemination of Disability Research


Systematic Reviews and Meta-analyses of
Single-subject Experimental Designs (SSEDs)

Holiday Inn – National Airport (Arlington, VA)
October 23, 2008

Ralf W. Schlosser, PhD (Northeastern University)
Oliver Wendt, PhD (Purdue University)

Download the Abstract (Word Doc 40kb)     


This workshop will provide an overview on how to conduct a systematic review and meta-analysis of single-subject experimental designs (SSEDs). SSEDs typically rely on within-subject experimental controls and use of time series data to establish the effectiveness of an intervention (Kennedy, 2005). The adoption of evidence-based practice (EBP) in disability, health care and rehabilitation fields demands that practitioners do not rely on any one individual study but rather the aggregated evidence from a synthesis of studies using SSEDs. In EBP, systematic reviews and meta-analysis of SSEDs constitute one of the most persuasive forms of scientific evidence (Schlosser, 2003). Analog to the meta-analysis of randomized controlled trials (Sackett et al., 2000), meta-analyses of SSEDs rank higher on evidence hierarchies than an individual SSED (Schlosser & Raghavendra, 2004). In this workshop we will highlight the rationale for and potential contributions of systematic reviews and meta-analysis of SSEDs, and discuss issues related to how syntheses of SSEDs differ from traditional systematic reviews and meta-analyses. In particular, this workshop will focus on:


After completion of this workshop participants will be able to:

About the Presenters

Ralf W. Schlosser, Ph.D., is a Professor and Chair of the Department of Speech-Language Pathology and Audiology at Northeastern University. He is also the Director of Clinical Research at the Center for Communication Enhancement, Children’s Hospital Boston at Waltham. He has published several systematic reviews and meta-analyses of single-subject research, and conducted original single-subject experiments to study the effectiveness of augmentative and alternative communication. He is a current NIDRR grantee and former Distinguished Switzer Fellow, as well as a Fellow of the American Association on Intellectual and Developmental Disabilities (AAIDD) and the American Speech-Language and Hearing Association (ASHA). In addition, together with Dr. Jeff Sigafoos, he is a joint editor of Evidence-Based Communication Assessment and Intervention. Dr. Schlosser is actively involved in the Education Coordinating Group of the ( - abandon link - 4/2011) Campbell Collaboration (C2), and he serves as co-chair of the C2's new Disability Subgroup.

Oliver Wendt, Ph.D., is an Assistant Professor in Special Education, and Speech, Language, and Hearing Sciences at Purdue University. He teaches graduate courses on assistive technology, autism spectrum disorders, severe disabilities and single-subject research methods. His professional preparation is in early intervention for children with developmental disabilities. Dr. Wendt has conducted several systematic reviews and meta-analyses of single-subject experiments and is currently investigating non-regression-based procedures for effect size calculations in single-subject research. He is an active member in the ( - abandon link 4/2011) Education Coordinating Group and the ( - abandon link 4/2011) Methods Group of the Campbell Collaboration. Dr. Wendt serves as chair of the C2's new Special Education Subgroup.


Kennedy, C. H. (2005). Single-case designs for educational research. Boston: Allyn & Bacon.

Sackett, D. L., Straus, S. E., Richardson, W. S., Rosenberg, W., & Haynes, R. B. (2000). Evidence-based medicine: How to practice and teach EBM. Edinburg, Scotland: Churchill, Livingstone.

Schlosser, R. W. (2003). Efficacy of augmentative and alternative communication: Toward evidence-based practice. San Diego, CA: Academic Press.

Schlosser, R. W., & Raghavendra, P. (2004). Evidence-based practice in augmentative and alternative communication. Augmentative and Alternative Communication, 20, 1-21.

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NCDDR is funded by the
National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR)
Project Number: H133A060028
U.S. Department of Education