Category: Experimental Research

An introduction guide to Experimental research

Experimental research is one of the research methodologies adopted by PhD students. This is a type of scientific research. It involves using two sets of variables. One set of variables are kept constant whereas the other set of variables are studied as the subject of experiment.

The significance of using this research method is it aids in conducting experiments and collecting large amounts of data. 

Characteristics of experimental research

  1. Subjects are randomly assigned to their experimental conditions.
  2. A researcher is able to modify an independent predictor variable.
  3. Subjects are treated similarly in regard to all variables involving different experimental conditions. This doesn’t apply to independent variables.

‘Cause and effect’ phenomenon

An experimental research is expected to establish an ‘cause and effect’ approach. The cause is the deciding factor based on which the effects are observed in an experiment. This is done to avoid any confusion that could arise because of naturally occurring events. Such events could make it hard to draw conclusions.

Hence, experimental research is carried in the following situations:

  1. The cause and effect phenomenon requires time as a vital factor. This factor establishes a relatIonship between the cause and the effect.
  2. There is an invariable behaviour between cause and effect.
  3. Desirability is the deciding distinct factor in the cause and effect relationship.

Types of experimental research

The experimental research designs are categorised into three types based on how the subjects are classified by the researcher. The basis of this organisation is done in accordance with various groups and conditions. The different types of this research design are:

1. Pre – experimental research design

This is the simplest of all the experimental research designs.Initially factors associated with the cause and effect of a phenomenon are considered. Based on them, a single group or groups in numbers are kept under observation for study.

This type of research design is further classified into three types:

  1. One shot case study research design
  2. One group Pretest-posttest research design
  3. Static group comparison

2. True – experimental research design

This is the most accurate design among the three experimental research designs. Here, statistical analysis is used to prove or disprove hypothesis.  This experimental research method is generally executed in experiments related to physical sciences. 

The significance of this design is that, this is the only research design that establishes a cause and effect relationship within a group or groups. A designs hould satisfy following factors to be recognised as a true-experimental research design.

They are:

  • Control group and experimental group
    1. A control group involves participants who are familiar with the experimental group but the rules of experimental group doesn’t apply to them. 
    2. Whereas, in the experimental group the participants have applied experimental research rules.
  • Researcher control variables
  • Random distribution

3. Quasi – experimental research design

As the name suggests, the quasi experimental design is a seemingly experimental design. The difference between an actual experimental research and a quasi-experimental research is the allocation of a control group. This type of research design is generally equipped in field settings which doesn’t involve random assignments.

Here, the participants are not randomly allotted as per conditions. The independent variable is controlled before calculating the dependent variable. The problem of directionality is eliminated in this setup. 

Types of variables used

Both dependent variables and independent variables are used. These variables are onl;y specific to experimental research. The variables used here can also be referred to as predictor and response variables. They are not specific and are used for all types of research.

  1. Independent variables

The researchers assigns values to the independent variables based on its effect on the dependent variables. The values are called as experimental conditions or treatment conditions. These values are alloted in accordance with the different groups. These groups can be divided into experimental groups and control groups. One can expand their study by adding more experimental groups.

The  independent variable is an equivalent of the predictor variable. 

2.Dependent variables

A dependent variable reflects the behaviour of the researcher in some aspects in relation to the independent variable.the dependent variable is equivalent to the response variable.

Why use experimental research

  • Researchers can manipulate the variables to get the desired results.
  • Any industry can implement this research as it is not subject or industry specific.
  • The research is extremely result driven.
  • Results can be applied to various other aspects after the completion of their analysis. 
  • The researchers are able to derive and analyze more details on the cause and effect of a hypothesis. 
  • This type of research can be conducted in association with other research methods. 

Limitations

  • An experimental design should operationalize the variables measured in a better manner. 
  • The research should consider factors such as study expectations, measuring outcomes, measuring variables, and answering methods for the research questions.  
  • While conducting an experimental research one could face limitations in the availability of the data and experimental setups that represent the actual scenarios.

Experimental Design Research Methodology – Between-Subjects Experimental Designs

In a between-subjects design, the subjects in each group are different; that is, different people serve in the control and experimental groups. The idea behind experimentation, is that the researcher manipulates at least one variable (the independent variable) and measures at least two groups or conditions. In other words, one of the most basic ideas behind an experiment is that there are at least two groups to compare. We typically refer to these two groups or conditions as the control group and the experimental group. The control group is the group that serves as the baseline or “standard” condition. The experimental group is the group that receives some level of independent level. Although we describe the two groups, an experiment may involve the use of two experimental groups with no control group. In other words, there can be multiple experimental groups in experiments. 

      Experimentation involves control. First, we must control who is in the study. We want to have a sample that is representative of the population about whom we are about to generalize. Ideally, we accomplish these pates in each condition in each condition, so we should use random assignment of subjects in two conditions. By randomly assigning participants to conditions, we are trying to make two groups as equivalent as possible. In addition to controlling all of this, we observe behavioural changes when the independent variable is manipulated, we can then conclude that the independent variable caused these changes in dependent variable. 

   Let’s consider the example of smoking and cancer to examine the difference between correlational research and experimental research. Remember, we said that there are positive correlational between smoking and cancer. We also noted that no experimental with human supported a causal relationship between smoking and cancer. Why is this case? Let’s think about trying to design an experiment determine whether smoking causes cancer in Humans. Keep in mind potential ethical problems that might arise as we design this experiment. 

  Let’s first determine the independent variable. If you identified smoking behaviour as the independent variable, you are correct. The control group would be a group that does not smoke, and the experimental group would be the group that does smoke. To prevent confounding of our study by previous smoking behaviour, we could only see non-smokers. We would then randomly assig them into either of the smoking or non-smoking group. In addition to assigning a subject to one of the two conditions, we would control all other aspects of their lives. This means that all participants in the study must be treated exactly the duration of the study, expect the half of them would smoke on a regular basis (we would decide when and how much) and half of them would not smoke at all. We would then determine the length of time for many years for us to access any potential differences between groups. During this time, all aspects of their lives that might contribute to cancer would have to be controlled-held constant between the groups. 

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                 FIGURE 9.1 Experimental study of the effects of smoking on cancer rates    

What would the dependent variable be? The dependent variable would be the incidence of cancer. After several years had passed, we would begin to take measures on the two groups to determine whether there were any differences in cancer rates. Thus, the cancer rate would be the dependent variable. If the control was maximized, and the experimental group and control group were treated exactly the same expect for the level of independent variable that they received, in any difference observe between the groups in cancer rate would have to be due to the only difference that existed between the groups- the independent variable of smoking. This experimental study is illustrated in Figure 9.1. 

 You should begin to appreciate the problems associated designing a true experiment to test the effects of smoking and cancer. First, it is not ethical to determine for people whether they smoke. Second, it is not feasible to control all aspects of these individual, lives of the period that is needed to conduct this study indicating that smoke causes cancer in humans.   

It is perfectly feasible, however, to conduct experimental studies on other topics. For example, if we want to study the effect of a certain type of mnemonic device (a study strategy) on memory, we could have one group use the device while studying. We could then give each person a memory test and look for a difference between performance in two groups. Assuming would have to be due to the independent variable. If the mnemonic group performed better, we could conclude the mnemonic device caused memory to improve. 

The memory study is also known as simple post-test-only control group design. We start with a control group and experimental group made up of equivalent subjects; we administrator the treatment (mnemonic or no mnemonic); and we take a post-test (after treatment) measure. It is very important that the experimental groups and control groups are equivalent because we want to be able to conclude that any differences observe differences observed between the two groups are due to the independent variable and not to some other difference between groups. We help to ensure equivalence of groups by using random assignment.