By: Diana Hammond and David L. Gast
Single subject research methodology is commonly used and cited in special education courses and journals. This article reviews the types of single subject research designs published in eight refereed journals between 1983 and 2007 used to answer applied research questions. Single subject designs were categorized as withdrawal/reversal, time lagged, comparison, or combination designs. To analyze data for trends, data were aggregated and presented in blocks of five years. Data were used to present a description of changes in the use of single subject designs for each journal reviewed and across each type of single subject design. Though limited by the number of randomly reviewed issues, results indicate specific trends in single subject methodology. A total of 196 randomly identified journal issues containing 1,936 articles were reviewed. Of reviewed articles, 456 employed at least one single subject design and a total of 556 single subject designs were coded. Results indicate time lagged designs were published more frequently than withdrawal/reversal designs. Also, multiple baseline designs were published more frequently than multiple probe designs and replication of effects for time lagged designs occurred more often across participants/groups. For comparison designs, there was an increase in trend concurrent with an increase in published functional analysis. Data collected also indicated an increase in the use of combination designs.