Solomon Four Group Design

The Solomon Four Group Design is a research method that is sometimes used in social science, psychology and medicine. It can be used if there are concerns that the treatment might be sensitized by the pre-test. The four groups have four different experiences:

1. Pre-test, treatment, post-test
2. Pre-test, no treatment, post-test
3. Treatment, post-test
4. No treatment, post-test

The effectiveness of the treatment can be evaluated by comparisons between groups 1 and 2 and between groups 3 and 4.