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	Experimentell design med kontrollgrupp	Solomon Four-Group Design
Ämnesområde	Försöksplanering	Försöksplanering
Familj	Process / pipeline	Process / pipeline
Ursprungsår	1935 (Fisher); 1963 (Campbell & Stanley codification)	1949
Upphovsperson	Ronald A. Fisher; systematised by Donald T. Campbell & Julian C. Stanley	Richard L. Solomon
Typ	Experimental research design	True experimental design
Ursprungskälla	Campbell, D. T., & Stanley, J. C. (1963). Experimental and Quasi-Experimental Designs for Research. Rand McNally.	Solomon, R. L. (1949). An extension of control group design. Psychological Bulletin, 46(2), 137–150.
Alias	controlled experiment, true experimental design, randomized controlled design, treatment-control design	Solomon design, four-group design, Solomon four-group control design, S4GD
Närliggande	4	5
Sammanfattning	Control group experimental design is a fundamental experimental structure in which participants are assigned to at least two groups — a treatment group that receives the intervention and a control group that does not — so that the effect of the intervention can be isolated by comparing outcomes across groups. Randomisation of assignment strengthens causal inference by balancing known and unknown confounders.	The Solomon Four-Group Design extends the classic pretest-posttest control-group design by adding two groups that receive no pretest, enabling researchers to detect whether the pretest itself alters participants' responses to the treatment. Introduced by Richard L. Solomon in 1949, it remains the gold standard for isolating the independent effect of a pretest and for obtaining unbiased estimates of treatment efficacy.