Randomized Solomon Four-Group Experiment

Context:
- It can control for Pretesting Effect.
- …
Counter-Example(s):
- Nonrandomized Control Group Pretest-Posttest Experiment.
See: Posttest-Only Experiment.

References

(Dimitrov & Rumrill, 2003) ⇒ Dimiter M. Dimitrov, and Phillip D. Jr Rumrill. (2003). “Pretest-posttest Designs and Measurement of Change.” In: WORK: A Journal of Prevention, Assessment and Rehabilitation, 20(2).
- QUOTE: This RD involves two experimental groups, E1 and E2, and two control groups, C1 and C2. All four groups complete posttest measures, but only groups E1 and C1 complete pretest measures in order to allow for better control of pretesting effects. In general, the Solomon four-group RD enhances both internal and external validity. This design, unlike other pretest-posttest RDs, also allows the researcher to evaluate separately the magnitudes of effects due to treatment, maturation, history, and pretesting.

(Clark & Shadish, 2008) ⇒ M. H. Clark, and William R. Shadish. (2008). “ Solomon Four-Group Design.” In: doi:10.4135/9781412963947
- QUOTE: The Solomon four-group design is an experimental design that assesses the plausibility of pretest sensitization effects, that is, whether the mere act of taking a pretest influences scores on subsequent administrations of the test. For example, if respondents complete a questionnaire measuring their knowledge of science as a pretest, they might then decide to subsequently seek answers to a few unfamiliar equations. At the posttest they might then score better on the science test compared to how they would have scored without taking the pretest. Meta-analytic results suggest that pretest sensitization does occur, although it is more prevalent for some measures than others, and the more time passes between pretest and posttest, the less likely a testing effect will occur. In the Solomon four-group design, the researcher randomly assigns respondents to one of four cells constructed from two fully crossed factors: treatment (e.g. treatment and control) and pretest administration

(Henning & Henning, 2006) ⇒ Gavin Henning, and Terri Henning. (2006). “Experimental Designs."
- QUOTE: This design overcomes the external validity weakness in the above design caused when pre-testing affect the subjects in such a way that they become sensitized to the experimental variable and they respond differently than the un-pretested subjects.

(Solomon, 1969) ⇒ Richard L. Solomon. (1949). “An extension of control group design." Psychological Bulletin 46, no. 2 (1949): 137.
- ABSTRACT: An extension or modification of the currently used control group design is presented. It is shown that the use of a 3-group design, and in some cases a 4-group design, has potentialities for demonstrating and weighting certain interaction effects. Examples are presented.