The Solomon Four-Group Design is an experimental research design used to measure the effect of an intervention while controlling for pre-test influence. It is an advanced version of the Pre-test Post-test Control Group Design, addressing the potential bias that pre-testing may introduce.
VIDEO EXPLANATION
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Structure:
This design consists of four groups, randomly assigned:
1. Group 1 (Experimental with Pre-test) – Receives a pre-test, intervention, and post-test.
2. Group 2 (Control with Pre-test) – Receives a pre-test, no intervention, and post-test.
3. Group 3 (Experimental without Pre-test) – Receives only the intervention and post-test.
4. Group 4 (Control without Pre-test) – Receives neither a pre-test nor an intervention, only a post-test.
By comparing these groups, researchers can determine if changes in the post-test are due to the intervention or the pre-test effect.
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Example with a 200 Sample Size
Let's assume a study is conducted to test the effectiveness of a new teaching method on student performance.
Total sample size = 200 students
Each group = 50 students
Group Assignments:
1. Group 1 (Experimental with Pre-test) – 50 students
Pre-test → New teaching method → Post-test
2. Group 2 (Control with Pre-test) – 50 students
Pre-test → No new method → Post-test
3. Group 3 (Experimental without Pre-test) – 50 students
New teaching method → Post-test
4. Group 4 (Control without Pre-test) – 50 students
No new method → Post-test
Analysis:
If Groups 1 & 3 show better performance than Groups 2 & 4, the teaching method is effective.
If Groups 1 & 2 show similar pre- and post-test scores, the pre-test may have influenced results.
Comparing all groups helps determine if the intervention is genuinely responsible for improvements.
This design ensures that both the intervention’s effect and pre-test influence are properly accounted for, making it a strong experimental method.
