Evaluating Tribal Home Visiting Using Single Case Design

Single case design (SCD) is a scientifically rigorous research method used to measure the impact of an independent variable (or intervention) on single “cases” of study. A basic SCD usually has the following key features:¹

• The unit of intervention and analysis includes individual cases, which can be a single participant (e.g., an adult or child) or a cluster of participants (e.g., classroom, community).
• Each case in the study serves as its own comparison, so that dependent variables (or targeted behaviors) are measured repeatedly on the same case prior to the intervention and compared with measurements taken during and after the intervention.
• The dependent variable is measured repeatedly within and across different phases or levels of the intervention to allow for identification of patterns.

Data points for each case are graphed to compare an individual behavior across intervention phases and analyze the relationship between the independent and dependent variables.

Example: Single Case Design Study Results

Why Choose SCD?

SCD is an appropriate method when the targeted behavior (i.e., dependent variable) is sensitive to change and defined precisely to allow for consistent, repeated measurement. It’s also an appropriate design for studies with small sample sizes that may not have the desired power for the statistical analysis to detect an effect when there is one. SCD works well for some Tribal Home Visiting Program grantees that are serving a limited number of families.

In addition to being a good fit for small sample sizes, SCD is an alternative to traditional experimental comparison designs, which require one group to receive an intervention and another “control” group to not receive it. Some grantees feel that withholding a service from families for research purposes is not appropriate, so they avoid experimental designs unless a naturally occurring control group is available in the community. In many ways, SCD aligns well with the inclusive cultural beliefs of tribal communities, because each participant receives the intervention and serves as his or her own comparison.

SCD is most common in fields of psychology and education and is typically used in school settings using observational measures. Tribal Home Visiting Program grantees have used SCD in innovative ways to evaluate home visiting in tribal communities and to evaluate cultural enhancements to home visiting models.

How TEI Supports Grantees Using SCD

TEI provides technical assistance to grantees using SCD for their local evaluations in a variety of ways:

• Facilitating introductory Webinars on SCD with examples specific to home visiting
• Connecting grantees with leading researchers in the field of SCD for assistance with their evaluation plans
• Coordinating SCD learning circles for peer sharing and discussions on the analysis and reporting of SCD findings

RESOURCES

• Single Case Design Brief: Selecting Appropriate Single Case Designs for Evaluating MIECHV Funded Home Visiting Programs (PDF, 412kb)
• What Works Clearinghouse, Single-Case Design Technical Documentation (PDF, 554kb)
• TEI Slide Show: Introduction to Single Case Design (PowerPoint, 13.1mb)
• TEI Slide Show: Using Single Case Design To Evaluate Home Visiting (PowerPoint, 2.5mb)

FOOTNOTE

1. Kratochwill, T. R., Hitchcock, J., Horner, R. H., Levin, J. R., Odom, S. L., Rindskopf, D. M., & Shadish, W. R. (2010). Single-case design technical documentation. Retrieved from What Works Clearinghouse.