Insights into Top 5 Characteristics of Experimental Research Design

Often, research in psychology, pure science and social science involves assessing causal hypothesis which requires well-planned experiments that deliver valid results. Achieving valid results requires a research design that reduces all kinds of biases. This is when experimental design comes into the picture. 

Experimental design involves manipulation of one or more independent variables to measure their impact on the dependent variable. This ‘gold standard’ is considered as one of the most powerful techniques to assess the cause-effect relationship and is commonly used when (a) there is time priority in a causal relationship, (b) there is consistency in a causal relationship, and (c) there is greater magnitude of correlation. 

Experimental design, divided into true experiments & quasi-experiments, require strict adherence to rigorous steps such as:

  • Identifying the research problem

  • Developing the experiment

  • Performing the experiment

  • Determining the validity of results

This research design, based on the comparison between two or more groups, includes features such as:

  1. Randomization - After developing a sampling approach, a researcher is required to randomly assign individuals to the different study groups in order to eliminate bias of individual differences in all study groups. Randomization lets you create homogenous treatment groups without involving potential judgements or bias. While randomly assigning participants, all participants have equal probability of being in a given condition. Here the participants are assigned to group receiving treatment (experimental group) or group with doesn’t require any kind of treatment (control group). The added benefit of this feature is that it neutralizes factors other than the independent & dependent variables. 

  2. Control over extraneous variables - The ‘control’ concept plays a vital role in experimental design. Random assignment results in concern of controlling extraneous variables (factors that affect the cause and effect relationship). While conducting the study, it is a must for scholars to control the differences between the groups via matching of group members, random assignment or statistical control of differences. However, while controlling the variables, the scholar must make sure that the treatment is administered in a similar way in each attempt. Upon the completion of the experiment, both the treatment group and control group should be assessed to identify the existence of differences between them. 

  3. Manipulation of variables - Experimental design involves manipulation of variables which are hypothesized to influence the outcome of interest. That is, at least one independent variable is manipulated to determine its response on the dependent variable. However, the type of independent variable varies according to a study. It can be explanatory, controlled, predictor, treatments, or input variables. During the study, one can vary the independent variable by creating two conditions, while looking for mediating process and effectiveness of the treatment. For instance, a scholar might vary the research subject receiving the treatment and the level of treatment.

  4. Validity of results - Achieving internal and external validity in studies such as social science is arduous. The crucial threat to internal validity occurs when the research participants refuse to take part in the study or are dropped out of the study. If the experiment is valid internally, then we can conclude that the independent variable has caused the outcome of the study. If the subjects are randomly assigned to control groups, the independent variable causes observed outcome. In addition to internal validity, external validity is a matter of concern in social science study. It is hard to generalize experimental outcomes to groups which are not included in a particular study. 

  5. Ethics - It is particularly essential to follow ethical guidelines in experimental research. The basic ethical principle includes:

(a) Respect for individuals - The individuals shouldnt be forced to take part in the study. One should take the consent of individuals and the study findings must be kept confidential. Also, the identity of the research participants should be protected.

(b) Beneficence - The experiments shouldn’t cause any harm to the individuals. The scholars should ensure to minimize the risk for research participants while maximizing the benefits for outcomes of study.

(c) Justice - It is a must for justification of all kinds of differential treatment among the research participants. 

Experimental design has several advantages when compared to other forms of research design like observational design, etc. 

  • Provides researchers with high level of control

  • Findings of the study can be replicated

  • Offers specific conclusions for a study

  • Natural setting can be replicated swiftly

  • Lets you determine the cause-effect relationship

  • Can be collaborated with other research designs 

To conclude, experimental design aims at drawing conclusions by controlling the extraneous factors to provide precise conclusion. However, while deploying this research design, you should consider the threat to internal validity and then reconsider them after the completion of the study.


How to manipulate the variables in experimental design?

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