Solomon Four Group Design – The Applications of the Research Method

Solomon Four Group Design

Solomon Four Group Design, an experimental design that examines the plausibility of the pretest sensitization effect. Its meta-analytic results concluded that pretest sensitization occurs. Although its prevalence varies for some measures, the more time passes between the pretest and posttest, the less likely a testing effect will occur.

For example, a respondent solved a questionnaire to assess their knowledge of maths as a pretest and later decided to seek answers for some unfamiliar equation. Due to this, they might be able to score well in the posttest. This verifies that there is a significant influence of pretesting on subsequent posttest results.  

Let’s have a further insight into applications and advantages of using Solomon four-group design in your research. 


Richard Solomon introduced this experimental design in 1949. Moreover, it examines the presence of the effects of pretest sensitization. Also, is sufficient to assess the treatment effects and is mostly immune from threats to internal validity. 

Furthermore, it has a high degree of external validity in contrast with the posttest only control group and pretest-posttest control groups. Therefore, it is the most desirable design among all basic experimental designs.


This research design is used in psychology, social sciences, and medicine. It is mostly used when there is concern that the treatment might be sensitized by the pretest. The Solomon four-group design involves individuals being randomized into four groups: two treatment groups and two control groups. 

Additionally, One of the two treatment groups receives a pre-test, whereas the others are post-tested. All four groups have different experiences. Hence, the effectiveness of the treatment can be estimated by comparing all these groups.

Why Isn’t Every Experiment A Solomon Four Group Design?

It is a standard research design for educational and sociological research that combats most internal and external validity problems apparent in lesser designs. Despite its statistical power and easily generalized results, complexity is one of the major drawbacks that prevent it from becoming a commonly used method. 

Moreover, to use this design, one must-have resources and time to implement all the four research groups. In tightly funded research.

Also, the statistics involved in this research design is severely complex, even in the era of computers and technologies. Unless the research is funded on a large scale or critical and has a competent team of researchers, most experiments are of simpler pretest-posttest research design. 

If the researcher is fully aware of any external validity issues, or generalization, they are robust enough and don’t need to apply Solomon four-group design. 

Solomon Four Group Design In Nursing

There has been an increase in applied research in the field of nursing. Not to forget the experimental research that has grown out of basic excellent research. One of the most meticulous designs that could be used in qualitative studies is Solomon Four Group Design. This is because it provides effective and efficient tools for determining cause and effect relationships and also provides adequate control of other variables that may interfere with the validity of the study. 

However, there is a paucity of using it in the field of nursing. The researcher gains confidence in the authenticity of the concluding analysis of the study as it protects against both threats to internal and external validity because of its thorough design.  

Although the use of this researching design is hardly rare in published nursing researches. Its complex design can make it more challenging as nursing researches involve human subjects. 

Advantages of the Solomon Four-Group Design:

It is one of the three primary designs with reliable experimental research but also can be used in quasi-experimental studies. This design is a mixture of the pretest-posttest control; group and the only posttest design. 

Having an advantage of the other two designs along with being able to test and control for instrument reactivity. Investigators using this design have the advantage to examine both the naib effects of testing as well as the interaction of the testing and treatment.

 As it’s known that subjects are randomly assigned in four groups so only two receive the treatment and others don’t. Some researchers choose a modified version in which there’s only one control group and that group is given the post and pretest. 

Importantly, Solomon’s design is the only one that examines pretest sensitization which significantly limits the generalizability of the research. 

Moreover, it helps the researcher to test and separate the effects of pretesting and treatment. Also, there is a minimum subject variation which maximizes the power of the study to find true treatment effects.

Why Is Solomon Four Group Design Underused? 

There are four major reasons why Solomon four-group design is underused in the growing field of research. First is the requirement of twice the number of groups making it complex and time-consuming. Second, rarely any researcher gets interested in assessing pretest sensitization effects. Third, the complexity of the analyzing materials adversely affects it. 

In simple words, the excessive number of group comparisons makes the result more complicated. Hence affects its reliability. Fourth, its complex design decreases the certainty concerning the proper statistical treatment. All these factors adversely affect the use of this research design.


A qualitative method research’s potential weakness is the intrusive nature of the testing along with specific pretesting. The Solomon four-group design helps to eradicate this complexity. 

However, its statistical issues cause hindrance, which is why there are only a few pieces of research on the ground of this research design. Moreover, it is no secret that this design has four groups. Where two receive treatment and the other two don’t. 

Similarly, two of the groups receive a pretest and the other two don’t. Also, to experimentally examine whether there is a threat operating or not, you can openly include testing as a significant factor. Solomon’s design applies to a different variety of tests. This helps to remove various problems causing elements and allows us to examine the effects of these changes. Moreover, for a reliable result, you should implement several tests of four sets.

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Alex Mehak
I Alex Mehak, studied at harvard university. Currently, I am working as a marketer for the website TechActives.com I am passionate about writing blogs and articles, especially in the field of technology. You can visit many of the websites to find out my valuable articles.