What is the Solomon four-group design

The Solomon Four-Group Plan and Pretest Sensitization Effects in Psychology

Hrobath, Bernhard (2015) The Solomon Four-Group Plan and Pretest Sensitization Effects in Psychology.
Diploma thesis, University of Vienna. Faculty of Psychology
Supervisor: Voracek, Martin
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Abstract in German

The Solomon four-group plan (a special experimental design) was introduced over 65 years ago, but has not yet been used too often. The design is particularly suitable for examining the effects of intervention and pretest as well as their interaction (pretest sensitization) and has a high level of prestige. The pretest sensitization effect represents a potential problem in various areas of psychology. Results on the occurrence of this effect are not available to a sufficient extent. Evaluating the data from the Solomon design is not that easy. Several methods have been proposed, some of which are controversial. Studies with the Solomon four-group plan from recent psychological research (from 1998) were systematically identified. The main aspects of the analysis were the evaluation methods used, the reporting and the effects found, with a focus on pretest sensitization. In addition, the descriptive investigation of the structure of the effects using interaction diagrams is demonstrated. The results of 53 analyzed studies show that the Solomon design is often used in the context of education and health research. In the process of analysis, frequent misinterpretations of the design and its implementation were observed. The evaluation methods show weaknesses: only 53% of the more recent studies (published since 1998) use state-of-the-art methods. The investigation or reporting of pretest effects or pretest sensitization effects is often not available. A pretest sensitization effect was reported in at least one of the scales examined in 9 studies; the effects here are in the small to medium range. For future applications of the Solomon design, it is recommended to take into account the particularities associated with this design and to use strong, adequate evaluation methods. An analysis of the effects typical of the design and a full report of the results should become the standard.

Keywords in German

Solomon four-group plan / Solomon design / pretest sensitization / pretest effect

Abstract in English

More than 65 years ago, the Solomon-four-group-design (a special format of experimental design) was presented - but has been underused until now. The design is especially appropriate for the identification of effects of a certain treatment, a given pretest and the interaction of those two factors (pretest-sensitization). It is often referred to as a design with high prestige. The mentioned pretest-sensitization effect is of particular concern in some fields of psychological science, but evidence for this effect is rare. The statistical analysis of the Solomon design is rather complex. Different methods have been proposed. A systematic review of studies using the Solomon design in recent (after 1998) psychological research. One target question was the implementation and chosen method of analysis. Another objective was the assembly of information about the pretest sensitization effect and its reporting in the studies. Interaction plots are used to further investigate the effects and demonstrated as a method for graphical representation of results in the Solomon design. Fifty-three studies were included in the analysis. The scientific fields education and health appeared as the sectors where the design is mainly used. The review process revealed some common mistakes and misinterpretations of the Solomon design. Results also indicate a lack of usage of appropriate methods. Only 53% of recently published (after 1988) studies use methods considered as state of the art. Reporting and analysis of pretest effects and pretest-sensitization effects are often ignored. Nine studies reported a pretest-sensitization effect in at least one variable, where the effect size (when reported) ranged from small to middle sized). Future studies with the Solomon design, should address the special characteristics of the design with regard to the usage of adequate statistical methods and reporting. The analysis of the specific effects and thorough reporting should be standard in the future.

Keywords in English

Solomon-four-group-design / Solomon design / pretest-sensitization / pretest effect

Document Type: University thesis (diploma thesis)
Author:Hrobath, Bernhard
Title:The Solomon Four-Group Plan and Pretest Sensitization Effects in Psychology
Subtitle:a systematic review
Circumference:92 pages: diagrams
Institution:University of Vienna
Faculty:Faculty of Psychology
Degree title or
University course (ULG):
Degree in psychology
Publication year:2015
Language:ger ... German
Supervisor:Voracek, Martin
Assessor:Voracek, Martin
Classification:77 Psychology> 77.03 Methods and techniques in psychology
AC number:AC13071391
Document ID:40481
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