Visual Analysis Tool
Single case design is a research methodology commonly used in behavioral sciences, especially the field of special education. It is an experimental research design in which participants act as their own control by getting exposed to both baseline and intervention conditions. Participant data are presented in a line graph and then interpreted through the process of visual analysis (Gast & Ledford, 2018).
Visual analysis is used to evaluate experimental control and determine the presence of a functional relation between the independent and dependent variables. There are two types of visual analysis – formative visual analysis and summative visual analysis. Formative visual analysis is used during the course of the study to make data-based decisions, such as when to change conditions or make modifications to the intervention. Summative visual analysis is used after the study is completed to determine both the presence and strength of the functional relation. A strong functional relation indicates that the intervention very likely caused behavior change (Barton et al., 2018).
The visual analysis tool is a spreadsheet designed to guide users through the summative visual analysis process in a step-wise, systematic way. The VA tool, intended for researchers, students, and others already familiar with visual analysis, is used to help determine if graphs demonstrate a functional relation and how confident the user is in that functional relation. The VA tool may be used to examine one or multiple graphs, either within a single study or across studies.
Visual Analysis Tool and Resources
Click the link below to download a copy of the visual analysis tool as an Excel spreadsheet. Written directions for using the tool can be found on the first tab of the spreadsheet.
This video provides detailed directions for using the VA tool as it walks users through each step.
Alternating Treatments Design Example
This video provides an example of using the VA tool with a study that included an alternating treatments design (ATD). Click the links below to download a copy of the article used (Pokorski et al., 2019) and the completed spreadsheet.
Withdrawal Design Example
This video provides an example of using the VA tool with a study that included a withdrawal design. Click the links below to download a copy of the article used (Luke et al., 2014) and the completed spreadsheet.
Barton, E.E., Lloyd, B.P., Spriggs, A. D., & Gast, D. L. (2018). Visual analysis of graphic data. In J. R. Ledford & D. L. Gast (Eds.), Single case research methodology: applications in special education and behavioral sciences (3rd ed., pp. 179-214). Routledge.
Gast, D. L., & Ledford, J. R. (2018). Research approaches in applied settings. In J. R. Ledford & D. L. Gast (Eds.), Single case research methodology: applications in special education and behavioral sciences (3rd ed., pp. 1-26). Routledge.
Luke, S., Vail, C. O., & Ayres, K. M. (2014). Using antecedent physical activity to increase on-task behavior in young children. Exceptional Children, 80(4), 489-503.
Pokorski, E. A., Barton, E. E., & Ledford, J. R. (2019). Assessing the differential effects of known and mystery rewards in a preschool-based group contingency. Journal of Early Intervention, 41(3), 256-275.