Control Group Approaches to Identify Impact

Published28th August 2014

This guide looks at research approaches that use comparison groups to measure and compare the difference made by voluntary, community and social enterprise organisations (VCSE). This includes research in which outcomes for groups of service users are compared to outcomes for groups that have not used a service, or have used different services. It also discusses research where a comparison groups are derived statistically, known as quasi-experimental approaches.

Good comparison group studies provide a high standard of evidence2, but compared to other evaluation approaches they are harder to get right. It‰Ûªs therefore worth familiarising yourself with other approaches to evaluation such as theory of change, qualitative research and outcomes tools before considering comparison groups.

The aims of this guide are to:

-Introduce the concept of comparison groups and why they are seen as a high standard of research.

-Help you think about options you may have to use comparison groups to evaluate your own interventions.

-Highlight the issues to consider when thinking about comparison groups.

This guide does not provide detailed instructions on how to design and run studies, but does provide links to these if you are interested. If you do identify an opportunity to conduct a comparison group study for your work, we strongly recommend you seek expert advice as early as possible in the process to ensure the study is robust and useful.

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