Research Writing

What is experimental research design/When to conduct/types

Experimental research is any research conducted with a scientific approach, where one set of variables is held constant, while the other set of variables is measured as the subject of the experiment. What is experimental research design?

Experimental research is one of the main quantitative research methods .

The simplest example of an experimental investigation is a laboratory test. As long as the research is conducted under scientifically acceptable conditions, it qualifies as an experimental research.

A true experimental investigation is considered successful only when the investigator confirms that a change in the dependent variable is due to manipulation of the independent variable.

It is important for an experimental investigation to establish the cause and effect of a phenomenon, which means that it must be clear that the effects observed in an experiment are due to the cause.

Of course, it may be that the events that occur are confusing and do not allow researchers to easily draw conclusions.

For example, a cardiology student conducts research to understand the effect of food on cholesterol and it turns out that most patients with heart problems are not vegetarians or have diabetes, it is because they eat meat (let’s say). The latter can be an aspect (cause) that can lead to a heart attack (effect). What is experimental research design?

Typical Designs and Features in Experimental Design

  • Pre and Post Test Design
    Check if the groups are different before the start of manipulation and the effect of manipulation. Previous tests sometimes influence the effect.
  • Control Group Control
    groups are designed to measure research bias and measurement effects, such as the Hawthorne effect or the Placebo effect . A control group is a group that did not receive the same manipulation as an experimental group. Generally, experiments have 2 conditions, but they rarely have more than 3 conditions at the same time.
  • Randomized and Controlled Clinical Trials Random
    sampling, comparison between an Experimental Group and a Control Group, and strict control / randomness of all other variables.
  • Solomon’s Four-Group Design
    With two control groups and two experimental groups. Half of the groups have a previous test and the other half do not. This is to test both the effect itself and the effect of the pretest.
  • Design Between Subjects
    Grouping of the participants according to the Different Conditions.
  • Intra-Subject Design What is experimental research design
    Participants participate in the Different Conditions – See: Repeated Measurement Design .
  • Counterbalanced Measurement Design
    Test the effect of the order of treatments when no control group is available or ethical.
  • Design of Similar Subjects
    Group participants to create Similar Experimental and Control Groups.
  • Double Blind Experiments
    Neither the researcher nor the participants know which is the control group. The results may be affected if the researcher or the participants know.
  • Bayesian Probabilities
    Using Bayesian probabilities to “interact” with participants is a more “advanced” experimental design. It can be used to make adjustments when there are many variables that are difficult to isolate. The researcher starts with a set of initial beliefs and tries to adjust them depending on the response of the participants. What is experimental research design?

When to conduct experimental research?

  •      When time is a vital factor in establishing a relationship between cause and effect.
  •      When there is an invariable behavior between cause and effect.
  •      When eminently the cause-effect relationship is for convenience.

Types of experimental research design

There are three main types of experimental research designs:

The different types of experimental research design are based on the way the researcher classifies subjects.

1. Pre-experimental design

This is the simplest form of experimental research design. A group, or several groups of people, are kept under observation after factors with cause and effect are considered. It is usually done to understand whether more research is needed on the target groups. What is experimental research design?

Pre-experimental research is divided into three types:

  • Investigation design of an instance.
  • Research design of a group
  • Comparison of two static groups.

2. True experimental design

This design is the most accurate form of experimental research design, as it relies on statistical analysis to prove or disprove a hypothesis. It is the only type of experimental design that can establish a cause and effect relationship within one or more groups. In that design, there are three factors that must be considered: What is experimental research design

  •      Groups: Control group and experimental group
  •      Variable: which can be manipulated by the researcher
  •      Distribution: random

This experimental research method is commonly implemented in the physical sciences.

3.- Quasi-experimental design

The word “quasi” indicates similarity. A quasi-experimental research design is similar to experimental research, they are almost the same. The difference between the two is the assignment of a control group. In this research design, an independent variable is manipulated, but participants in a group are not randomized. The independent variable is manipulated before calculating the dependent variable and thus the directionality problem is eliminated. Quasi research is used in field settings where random assignment is irrelevant or not required.

Advantages of experimental research

  • Researchers have stronger control over the variables to obtain the desired results.
  • Subject or industry is not a criterion for experimental research because any industry can implement it for research purposes. What is experimental research design?
  • The results are extremely specific.
  • The cause and effect of a hypothesis can allow researchers to analyze more details.
  • Experimental research can be used in association with other research methods .

Examples of Experiments

This website contains many examples of experiments. Some are not true experiments , but rather include some kind of manipulation to investigate a phenomenon. Others meet most or all of the criteria for true experiments.

Here are some examples of science experiments:

Social psychology

  • Stanley Milgram Experiment – Do people obey orders even though they are clearly dangerous?
  • Asch’s experiment – Do people conform to the group’s behavior?
  • Stanford Jail Experiment – How do people react to roles? Would you behave differently?
  • Good Samaritan Experiment – Would you help a stranger? – Explanation of the helping behavior.


  • Law of Segregation – Mendel’s Pea Experiment.
  • Transformation Principle – The Griffith Experiment on Genetics.


  • Ben Franklin’s Kite Experiment – Struck by Lightning.
  • JJ Thomson’s Cathode Ray Experiment



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