Introduction

Experimental design is one of the quantitative research approach designs. In this blog, https://researchmethodsclass.com/research-approaches-understanding-quantitative-research-approach/, we have discussed the quantitative research approach in detail, as well as Survey and Ex-Post Facto, which are quantitative research designs.

This blog will explore the third research design in the quantitative research approach, which is Experimental Designs.

Suppose a researcher wants to investigate whether using digital learning materials improves students’ performance in Mathematics. How would the researcher establish that any improvement in students’ performance was caused by the digital learning materials, not by other factors such as students’ previous knowledge, teachers’ experience, or the amount of time spent studying?

This is where experimental research design becomes important.

What is Experimental Research Design?

Experimental research design refers to a systematic plan or structure that guides a researcher in manipulating an independent variable and observing its effect (changes) on a dependent variable under specified conditions.

In simple terms, it is a research plan that enables a researcher to investigate whether changing one variable produces a change in another variable.

Experimental design is particularly useful when a researcher wants to establish a cause-and-effect relationship between variables. Unlike descriptive or correlational research, where researchers observe variables as they naturally occur, experimental research involves introducing or manipulating a particular condition (the independent variable) to determine its effect on another variable (the dependent variable). A cause – and –effect relationship (or a causal relationship) enables a researcher to conclude that variable A caused variable B to occur.

For example, a researcher may introduce digital learning materials to one group of students and use the conventional learning materials with another group. At the end of the intervention, the researcher compares the academic performance of the two groups to determine whether the digital learning materials produce better results.

Establishing a cause-and-effect relationship is not always straightforward. Other factors, apart from the independent variable, may influence the outcome of a study. These factors are known as extraneous variables. Researchers must therefore understand how to identify and control for extraneous variables to ensure that their findings are valid and reliable.

Before Conducting an Experimental Study,

1. Two homogeneous groups must be identified. For instance, students in the same grade. One group is called the Control Group, and the other group is called the experimental group or the treatment group;
2. The Experimental or treatment group is given the treatment, while no treatment is given to the control group. In this case, the experimental group is taught using the digital learning materials while the control group is taught using conventional learning materials;
3. After the experiment, the effects of the treatment (intervention) are then ascertained by comparing the behavior of the treatment or experimental group) with that of the control group.

To demonstrate Causality, the researcher must be aware of:

1. Independent variable (IV)

The independent variable is the variable that the researcher deliberately manipulates, introduces, or changes to determine its effect on another variable.

For example, if a researcher wants to investigate the effect of digital learning materials on students’ academic performance, the use of digital learning materials is the independent variable.

• Dependent Variable (DV)

The dependent variable is the outcome or response that the researcher measures to determine whether it has changed as a result of manipulating the independent variable.

In the example above, students’ academic performance is the dependent variable.

• Extraneous Variables and Spurious Relationship

These are other variables, apart from the independent variable, that may influence the dependent variable and affect the research findings. For example, students’ previous academic ability, motivation, parental support, and teachers’ experience may influence academic performance independently of the teaching method being investigated.

A spurious correlation is a common misinterpretation of cause and effect. It occurs when two variables are statistically related but not causally related. That means the presumed cause of an effect is actually caused by an unseen or unconsidered variable

Consider this: Many people assert that smoking causes Lung Cancer. If this were so, why do people who do not smoke get Lung Cancer? Therefore, the relationship between smoking and lung cancer is a spurious relationship.

Controlling for Extraneous Variables

One of the key things in an experimental study is to control for extraneous variables. To control for extraneous variables means removing the effect of any other IV (apart from the one under consideration) that may have a similar effect on the DV.

Extraneous variables are variables other than the independent variable that may influence the dependent variable and potentially affect the results of an experiment.

For example, suppose a researcher wants to investigate whether the use of digital learning materials improves students’ academic performance.

The independent variable is the use of digital learning materials, while the dependent variable is students’ academic performance.

However, academic performance may also be influenced by:

1. Students’ previous academic ability.
2. Students’ motivation to learn.
3. Teachers’ teaching experience.
4. Availability of learning resources.
5. Parental support.
6. Time allocated for learning.
7. Students’ socioeconomic backgrounds.

These are potential extraneous variables because they may influence academic performance independently of the intervention.

If the researcher does not consider these variables, it may be difficult to establish whether the observed improvement in academic performance resulted from digital learning materials or from other factors.

To be continued…