Experimental research encompasses various designs to study a phenomenon. There are different types of experimental designs that you can use for experimental research. But the design of the experiment has a significant impact on the study’s findings and outcomes. So, it is important to know about the pros and cons of various experimental designs. It will help you decide which experimental design is appropriate for your research.
What is an experimental design?
Researchers conduct experiments to determine the causal relationships between variables. Researchers seek to establish correlations between independent and dependent variables. Experimental design refers to establishing standard procedures and methodical tests to test a hypothesis. Experimental design enables the researcher to conduct research in an impartial and structured manner. It enhances the accuracy of the results and leads to valid conclusions concerning a hypothesis. The purpose of experimental designs is to understand the impact of an independent variable on a dependent variable.
What are the different types of experimental design?
1. Pre-experimental research design
Pre-experimental research design is the most basic design researchers use in experimental research. Researchers observe the impact of an independent variable on a group or various groups. The purpose is to seek the assumed impact of an independent variable on the dependent groups. There are no control groups in this research design, and it is the most basic design. Researchers use this design at a preliminary stage to determine whether they should investigate a particular group or not. There are three sub-types of pre-experimental research design:
· One-shot case study research design
This type of research design encompasses one dependent group or a variable. Researchers use this method after assessing the presumed impact of an independent variable. Also, they contrast the case study to broad predictions of what the situation would have been if there was no presumed impact. Researchers do not use any control or comparison groups.
· One-group Pretest-posttest Research Design
Researchers observe two cases at two different times. One case is studied before the assumed impact of treatment, and another is studied after the treatment. The outcomes of the test are assumed as a result of an intervention. In this design also, researchers do not use any control or comparison groups.
· Static Group Comparison
A static group comparison experimental design encompasses the observation of two or more groups. Researchers seek the impact of treatment on one group, whereas the other groups remain constant. Researchers then repeat the tests on all of the groups. The disparities between the different groups are evaluated based on the presumed impact of treatment on one group while holding the other groups static.
a) Pros of pre-experimental research design
· Pre-experimental research design is exploratory.
· An economical research design that helps researchers determine whether a plausible answer is worth investigating further
b) Cons of Pre-experimental research design
· It involves no comparison or control groups; therefore, it rules out the possible impact of confounding variables and other explanations.
· It does not fulfil the validity and reliability criteria of the scientific process.
2. Quasi-Experimental Research Design
The prefix quasi denotes similarity. As a result, quasi-experimental research mimics experimental research but is not actual experimental research. The researcher does not select the participants randomly; instead, they are selected based on non-random criteria. The purpose of quasi-experimental research is to seek the relationship between cause and effect. However, unlike full-experimental research, a quasi-experimental research design is useful for scenarios where it is difficult to randomise. Researchers manipulate the independent variable before the measurement of the dependent variable. It eliminates the problem of directionality. However, researchers select the participants based on non-random criteria; therefore, experimental research does not minimise the impact of confounding variables.
a) Advantages of Quasi-Experimental Research Design
· Useful in those scenarios where true experiments are not possible due to ethical and practical concerns
· Common in educational institutes where administrators do not allow the random sampling of students
· A useful tool in field research where random sampling is impossible to achieve
· Useful for understanding the utility of treatment usually in psychotherapy
· Economical and save time.
· The external validity is higher since the participant selection is non-random.
b) Disadvantages of Quasi-Experimental Research Design
· Non-randomised sample size leads to the exaggeration of effect and extent
· Lacks internal validity and fails to fulfil the criteria of causality
· Selection bias based on non-randomised participant selection
· Does not take measures to eliminate the impact of confounding variables
3. True Experimental Research Design
True experimental design is a statistical method for determining the causal relationship between independent and dependent variables. It is one of the most reliable types of experimental design. The reliability of the design is due to a lot of evidence to back up the existence of correlations. True experimental research design entails the fulfilment of the following three criteria:
· Control Group and Experimental Group
True experiments require a control group. A control group is a group of research subjects who look and act similar to the experimental group. But the control group does not undergo the experimental procedure. Also, the control group offers a precise benchmark against which the experimental results can be compared. The experimental group comprises study participants who are given the experimental treatment. True experiments should have at least one control group and one experimental group. However, the usage of several experimental groups is feasible.
· Presence of an Independent Variable
True experiments require the presence of an independent variable with the variation that the researcher manipulates the variable. However, the researcher manipulates the variable to observe its impact on the dependent variable.
· Random Assignment
Researchers have to assign the study participants randomly to the sample groups. Also, it means that every research participant has the same chance of getting assigned to the sample group. The benefit of random assignment is that it ensures that the variations between groups are truly random. The random assignment of study participants is necessary for both control and experimental groups.
a) Advantages of True Experimental Research Design
· Researchers can statistically analyse the results of true experimental design, which generates reliable results.
· It makes it possible for other researchers to replicate the experiment and generate similar results.
· Useful for natural sciences
b) Disadvantages of True Experimental Research Design
· Costly and Time-Taking
· Not useful for social sciences since social realities cannot be assessed in laboratory conditions
The choice of an experimental design for your research depends upon the aims and objectives of your research. But no matter which design you use for research; it is important to fulfil the scientific criteria.
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