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	Experimentell design med förtest och eftertest	Solomon Four-Group Design
Ämnesområde	Försöksplanering	Försöksplanering
Familj	Process / pipeline	Process / pipeline
Ursprungsår	1963 (formalized in Campbell & Stanley)	1949
Upphovsperson	Donald T. Campbell and Julian C. Stanley	Richard L. Solomon
Typ	Experimental / quasi-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	pretest-posttest design, before-after design, pre-post design, two-wave experimental design	Solomon design, four-group design, Solomon four-group control design, S4GD
Närliggande	5	5
Sammanfattning	The pretest-posttest experimental design measures participants on the outcome variable before and after treatment, typically with random assignment to treatment and control groups. The difference between pre- and post-scores isolates the treatment effect from baseline variation, making this one of the most widely used frameworks in experimental and quasi-experimental research across education, psychology, medicine, and the social sciences.	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.