One of the broad way to categorize research designs is to divide them into experimental and non-experimental research. There are various benefits and drawbacks of experimental research design over non-experimental research design and vice versa. There are various situations in which experimental research design can only work while in other situations only non-experimental research design can work. The selection of experimental and non-experimental research design only depends on the type of the research question and the field of study.
Experimental and non-experimental research design
Experimental research design
Experimental research designs are based on a clear hypothesis, the purpose of the research is to confirm or refute the validity of the hypothesis. Experimental research designs have an independent variable, a dependent variable, and a control group. Most of the experiments are conducted in a laboratory in a controlled environment. The purpose of the experiment is to find out the causation and experimental studies are causal studies. These studies answer what, why and even how questions in the research. The experimenter can manipulate the variables and he has a control group and a placebo. The control group receives the treatment that the experimenter wants to test and the placebo group is tested without any treatment. The change in the results of both groups are compared. The experimenter repeats the test in the same environment more than one time to get most valid results. There are basically three different types of experiments: controlled experiments, quasi-experiments, and field experiments.
The experimenter determines two groups to perform an experiment: one group is called the experimental group and the other group is called a placebo group. The experimental group gets the treatment and the placebo does not get any treatment. The experimental group is similar to the control group except that the control group does not get any treatment while the experimental group gets the treatment. The experimenter repeats the test twice or thrice to increase the validity of the results.
Non-experimental research design
Non-experimental research designs are carried out in natural settings, it does not involve manipulation of the situation, event, circumstances or people. Survey, case studies, correlational studies comparative studies and descriptive studies are some of the examples of non-experimental research design. Longitudinal studies are also non-experimental research and the purpose of these studies is to study a situation, people or phenomenon over a period of time to observe the change.
A correlation can be established using non-experimental research design but causation cannot be established. To establish causation, the researcher should be able to say that the result is the outcome of the observed variable and not something else. They do not have a control group and the research design is highly flexible. Due to the absence of the control group the researcher cannot ascertain that the final results are the direct effect of the variable that has been studied. The non-experimental research design study the phenomenon, people or situation in a natural setting without manipulating it, therefore, the findings can be applied to a wide audience.
In a non-experimental research, the researcher does not manipulate the variables to be tested and therefore he cannot ascertain the effect of the independent variable on the dependent variable. A causation is established in some of the nonexperimental studies but not in all of them. The causation is established by determining that a certain variable has an impact on another variable. It can also compare the results of two or more groups or people on one or more variables.