ARTICLE 28: Research Methods for Ph. D. and Master’s Degree Studies: Experimental Methods

Written by Dr Hannes Nel


Can lessons from events be gained in a laboratory?

Lessons that will apply to every place and all people?

You be the judge of that after reading this article.

Quantitative experimental methods

The essential feature or experimental methods is that you deliberately control and manipulate the conditions which determine the results in which you are interested.

To achieve this, you will need to introduce an intervention and measure the difference that it makes.

It is mostly used by people doing quantitative research and in natural sciences.

The precondition for research to be experimental is that it should meet the requirements for scientific research.

The requirements for scientific research are that the researcher must have control over the variables, careful measurement, and establishing cause and effect relationships.

An experiment involves making a change in the value of one variable – called the independent variable – and observing the effect of that change on another variable – called the dependent variable.

Using a fixed design, experimental methods can be confirmatory, seeking to prove or disprove a hypothesis, or explanatory, which would be discovering the effect of certain variables.

The variability and validity of experimental methods often depend on the ability to replicate the results from an experiment in similar situations and generalizing the findings to other similar situations.

You can, for example, test the psychological effect of the COVID-19 pandemic on people by asking them relevant questions during an interview.

You can also ask people to complete a questionnaire.

Responses to the questions can be measured in different ways, depending on the type and context of the experiment.

In the experimental methodology, generalization is referred to as “external validity”.

External validity means that the same results will be obtained with different groups and in different places.

You can imagine that external validity will not be easy to achieve.

This is mostly because of the number of different external variables that can influence your experiment.

The less external variables there are, the better will the chances be that you will achieve external validity.

Experiments can be experiments in a laboratory, field experiments or natural experiments.

Regardless of where the experiments are done, they require quite some planning and preparation.

Most, if not all, tests that are done in a laboratory are examples of experimental research.

Experiments in a laboratory

A laboratory experiment would be an experiment that is conducted under highly controlled conditions where accurate measurements are possible.

Laboratory experiments are mostly easy to replicate.

That is because standardized procedures and measurements of variables are used.

There are not many external variables over which you have no or little control.

Laboratory tests, however, do not always replicate real life, with the result that findings will probably not be generalizable outside the laboratory.

Field experiments

Field experiments are done in real-life environments.

The researcher still manipulates the independent variable but in a real-life setting.

Findings in field experiments should be generalizable to real-life settings.

A limitation of field experiments is that there will probably be many external variables that might bias the results.

Consequently, it would be difficult for other researchers to replicate the results.

Natural experiments

Natural experiments are also conducted in real-life environments.

They differ from field experiments in that the researcher cannot manipulate the independent variables – events occur as they would in real life.

Behavior in a natural experiment is more likely to reflect real life because of its natural setting.

It might be necessary for covert observation.

That is, the target group for the research does not know that they are being observed.

The reason for this is that people often behave differently when they know that they are being watched than they would normally behave.

This is even worse if they know that video footage is being taken of them.

Covert research can have ethical consequences which you should consider and remove in advance.

The researcher has no control over external variables that might bias the results.

Experiments in qualitative research

The parallel in qualitative research is when a part or the whole qualitative research study is the subject of attempted replication of a phenomenon or event.

For example, within a single qualitative research study, replication can sometimes be achieved by conducting more than one of the same or at least similar case studies.

The more similar the findings from the cases, the more a replication might be claimed.

However, replication is not always possible because of the dynamic nature of human phenomena.

Paradigmatic approaches that fit well with experimental methods include behaviourism, empiricism, modernism, phenomenology, scientism and symbolic interactionism.


In experimental research:

  1. You, as the researcher, manipulate the conditions for the research.
  2. You must have control over the variables.
  3. Careful measurement of phenomena or behavior will be necessary.
  4. You will need to establish a cause and effect relationship.
  5. External validity will not be easy to achieve.

Experimental methods can be confirmatory or explanatory.

An independent variable is the input variable, whereas the dependent variable is the outcome variable – the result.

It is not easy to achieve external validity with any of the experimental research types.

That is because of differences in variables between the place where the experiment is done and real-life conditions.

Experiments can be experiments in a laboratory, field experiments or natural experiments.

The conclusions of experimental methods can be achieved through qualitative research.


In closing,

I used one additional source of information for this article. That is McLeod, S.A. (2012, Jan 14) Experimental method. Simply psychology: https://www.simplypsychology/org/experimental-method.html. I accessed the source on 10 March 2020.

The main source of information that I use for all my articles and videos on Ph. D. and master’s degree research is my book entitled Preparing Qualitative Research Reports.

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