Solomon Four-Group Design
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.
Source record
Citations copied verbatim from the method’s source record. No claim-level verification is inferred from them.
- Solomon, R. L. (1949). An extension of control group design. Psychological Bulletin, 46(2), 137–150. · DOI 10.1037/h0062958
- Campbell, D. T., & Stanley, J. C. (1963). Experimental and Quasi-Experimental Designs for Research. Rand McNally. · ISBN 978-0395307878
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