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	Blockad Solomon fyrgruppsdesign	Solomon Four-Group Design
Ämnesområde	Försöksplanering	Försöksplanering
Familj	Process / pipeline	Process / pipeline
Ursprungsår	1949 (base); blocking extension applied in behavioral and social sciences from mid-20th century onward	1949
Upphovsperson	Richard L. Solomon (base design, 1949); blocking integrated from classical experimental design tradition (Fisher, 1935)	Richard L. Solomon
Typ	Experimental design	True experimental design
Ursprungskälla	Solomon, R. L. (1949). An extension of control group design. Psychological Bulletin, 46(2), 137–150.	Solomon, R. L. (1949). An extension of control group design. Psychological Bulletin, 46(2), 137–150.
Alias	Blocked S4G, randomized blocked Solomon design, Solomon four-group with blocking	Solomon design, four-group design, Solomon four-group control design, S4GD
Närliggande	6	5
Sammanfattning	The blocked Solomon four-group design combines Solomon's classic four-group structure — which disentangles pretest sensitization effects from treatment effects — with blocking on a known nuisance variable. Participants are first grouped into homogeneous blocks (e.g., by baseline ability, gender, or site), then randomly assigned within each block to one of four conditions: pretested treatment, pretested control, unpretested treatment, and unpretested control. This structure simultaneously controls for maturation, pretest reactivity, and block-level variance, making it one of the strongest quasi-controlled experimental frameworks available.	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.