Competency: Differentiates kinds of quantitative research.

Experimental research is usually undertaken when the goal of the research is to trace cause-and-effect relationships between defined variables. However, the type of experimental research chosen has a significant influence on the results of the experiment.

Therefore, bringing us to the different types of experimental research. There are 3 main types of experimental research, namely; pre-experimental, quasi-experimental, and true experimental research.

Pre-Experimental Research

Pre-experimental research is the simplest form of research, and is carried out by observing a group or groups of dependent variables after the treatment of an independent variable which is presumed to cause change on the group(s). it is further divided into three types.

• One-shot case study research

• One-group pretest-posttest research

• Static-group comparison

Quasi-Experimental Research

The quasi type of experimental research is similar to true experimental research but uses carefully selected rather than randomized subjects. the following are examples of quasi-experimental research:

• Time series

• No equivalent control group design

• Counterbalanced design.

True Experimental Research

True experimental research is the most accurate type and may simply be called experimental research. It manipulates a control group towards a group of randomly selected subjects and records the effect of this manipulation.

True experimental research can be further classified into the following groups:

• The posttest-only control group

• The pretest-posttest control group

• Solomon four-group

What is Non-Experimental Research?

Non-experimental research is the type of research that does not involve the manipulation of control or independent variable. In non-experimental research, researchers measure variables as they naturally occur without any further manipulation.

This type of research is used when the researcher has no specific research question about a causal relationship between two (2) different variables, and manipulation of the independent variable is impossible. They are also used when:

• subjects cannot be randomly assigned to conditions.

• the research subject is about a causal relationship, but the independent variable cannot be manipulated.

• the research is broad and exploratory.

• the research pertains to a non-causal relationship between variables.

• limited information can be accessed about the research subject.

There are three (3) main types of non-experimental research, namely; cross-sectional research, correlation research, and observational research.

Cross-sectional Research

Cross-sectional research involves the comparison of two or more pre-existing groups of people under the same criteria. This approach is classified as non-experimental because the groups are not randomly selected, and the independent variable is not manipulated.

For example, an academic institution may want to reward its first-class students with a scholarship for their academic excellence. Therefore, each faculty places students in the eligible and ineligible group according to their class of degree.

In this case, the student's class of degree cannot be manipulated to qualify him or her for a scholarship because it is an unethical thing to do. Therefore, the placement is cross-sectional.

Correlational Research

Correlational type of research compares the statistical relationship between two variables. Correlational research is classified as non-experimental because it does not manipulate the independent variables.

For example, a researcher may wish to investigate the relationship between the class of family students come from and their grades in school. a questionnaire may be given to students to know the average income of their family, then compare it with GPAs.

The researcher will discover whether these two factors are positively correlated, negatively correlated, or have zero correlation at the end of the research.

Observational Research

Observational research focuses on observing the behavior of a research subject in a natural or laboratory setting. It is classified as non-experimental because or does not involve the manipulation of independent variables.

A good example of observation research is an investigation of the crowd effect or psychology in a particular group of people. Imagine a situation where there are 2 ATMs at a place, and only one of the ATMs is filled with a queue, while the other is abandoned.

The crowd effect infers that the majority of newcomers will also abandon the other ATM.

You will notice that each of these non-experimental researches is descriptive in nature. It then suffices to say that descriptive research is an example of non-experimental research.