Experimental Research Design

Experimental research designs are the primary approach used to investigate causal (cause/effect) relationships and to study the relationship between one variable and another. This is a traditional type of research that is quantitative in nature. In short, researchers use experimental research to compare two or more groups on one or more measures. In these designs, one variable is manipulated to see if it has an effect on the other variable. Experimental designs are used in this way to answer hypotheses. A hypothesis is a testable statement that is formulated by the researcher to address a specific question. The researcher designs an experimental study which will then support or disprove the hypothesis.

To further the discussion of experimental research in future modules, it is important to understand the basic terminology related to experimental research. Following is a list of key terminology:

• Independent Variable – This is the variable that will be manipulated, the “cause” or treatment variable. This variable may be an activity or characteristic that the researcher believes will make a difference.
• Dependent Variable – This variable is the “effect” or outcome of manipulating the independent variable. The only constraint is that the outcome must be measurable.
• Experimental Group – The group that receives the treatment being investigated.
• Control Group – The group that remains the same in order to have something to compare the experimental group against.

Experimental research is based on a methodology that meets three criteria that are important if the results are to be meaningful. These criteria are as follows:

• Random Assignment – Test subjects must be randomly assigned to the treatment groups to control for creation of groups that may systematically differ in another way that impacts the outcome of the treatment.
• Experimental Control – All aspects of the treatments are identical except for the independent variable. If all other factors are controlled and kept constant, then if measurable differences are found in the outcomes, the researcher can be assured that the difference is due the independent variable (treatment).
• Appropriate Measures – The measures or outcomes must appropriate for testing the hypothesis. The outcome measured must represent the idea being tested in the hypothesis in order for the results to be valid.

Considering the definitions and criteria from above, it is now to time to explore an example of experimental research using those concepts.   Let’s say that a researcher wanted to investigate the effects of using flipped classroom teaching techniques in an American history course.  The hypothesis being tested is that the flipped classroom teaching style will result in higher test scores among the students. The researcher will begin by randomly assigning students into two different sections of the course. The first section will be taught using the traditional lecture format. The second section will be taught used flipped classroom teaching techniques. The learning objectives and content for both sections will be identical. Both sections will be given identical exams throughout the semester and the scores between the two sections will be compared to assess student learning. The flipped classroom teaching style is the independent variable. The dependent variable is the test scores. The experimental group is the section of the course where the flipped classroom technique is being used and the control group is the section that continues to utilize the traditional lecture format. This is a classic example of the use of experimental research design. The following modules will delve deeper into various aspects of experimental research.