In experimental research, researchers use controllable variables to see if manipulation of these variables has an effect on the experiment's outcome. Additionally, subjects of the experimental research are randomly assigned to prevent bias or error.
How Experimental Research Works Experimental research uses manipulation of variables in a controlled testing environment to gain an understanding of the causal processes associated with the subject matter. In many cases, experimental research uses randomly assigned test subjects assigned to either an experimental group or a control group. Researchers manipulate specific variables involved with the testing to determine if changing these variables has any affect on the experiment's outcome. Usually, but not always, researchers restrict changes to one variable at a time. Randomization is preferred as it is thought to reduce bias so that test subjects can't knowingly have an influence on the outcome of the experiment.
Types of Experimental Research In experimental research, researchers use three basic experiment designs: pre-experiment, true experiment and quasi-experiment, as explained in the section below.
- Pre-experimental research: In pre-experimental research, researchers follow basic experimental steps but do not use a control group. Pre-experimental research serves as the precursor, or preparation phase taking place before any true experimental research.
- True experimental research: True experimental research is the actual process of experimentally researching a subject. In true experimental research, sample groups are randomly assigned, one designated control group is assigned and only one variable can be manipulated at a time. In addition, any test subjects are assigned to the control or experiment groups randomly.
- Quasi-experimental research: Used extensively in psychology and the social sciences, quasi-experimental research is similar to true experimental research but does not use a random allocation of test subjects to a control or experimental group. In fact, quasi-experimental research may lack any control group at all, making analysis of the subject more difficult.
Types of Trials in Experimental Research When conducting the randomized testing in experimental research, researchers can use either single- or double-blind trials to further help eliminate bias.
- Single-blind trials: In a single-blind trial, test subjects do not know in which test group they are in or what they are having done to them as part of the experiment. In fact, test subjects only find out what group they tested in upon completion of the study.
- Double-blind trials: In a double-blind trial, neither participants or researchers know which test subjects are in an experimental or control group. This type of study helps reduce bias on the part of the researchers.
The Goals of Experimental Research Determining the affects of various variables on a test subject represents the final goal of experimental research. This allows researchers to see if changing one thing about an experiment can change its outcome. In this way, researchers can eliminate the affect of outside factors on a subject and draw conclusions about the relationships between the many variables involved in an experiment. By using randomization, the researchers can eliminate as much bias as possible which might have an effect of an experiments outcome. A major downside to this type of experimentation is the large amount of time it takes and the higher costs associated with it.