Students often have difficulty classifying quantitative research designs.
In quantitative research, designs can be classified into one of three categories: descriptive
non-experimental, quasi-experimental or experimental.
To identify which of these designs your study is using follow the steps in this video.
First, ask yourself if the researchers did anything to the participants.
More specifically, was there an intervention?
Interventions include things like support groups, educational sessions, treatments for
a condition or some other variable that is being tested.
If people would not normally have something without being in the study but the researcher
gives it to them to see what it will do than that is an intervention.
You may also see research texts call this a manipulation.
Essentially, the researcher did something to people to provoke some kind of measurable
result.
If the answer is yes, there was an intervention, then the study is either a quasi-experimental
or experimental.
I will tell you how to decide in a moment.
If the answer is no, the study is descriptive non-experimental.
Sure, you could be more specific in the description of the design, but for the purposes of grouping
your research in a literature review this label is often sufficient at an undergraduate
level.
Descriptive non-experimental studies may also be called observational.
Some examples of more specific labels include case control, cohort and correlational studies.
For more information about these non-experimental designs please visit the research playlist
below this video and watch the video about research paradigms and methodology.
To find out if the design is experimental ask yourself if it is a randomized controlled
trial.
Randomized controlled trials are considered the gold standard or "best" possible design
(in quantitative research).
You may also hear randomized controlled trails referred to as true experiments.
However, in the real world it is difficult to conduct a true randomized controlled trial
in many situations, which means that a lot of studies are done that are not classified
as randomized controlled trials.
Randomized control trials have three key components: a random sample, a control group and an intervention.
If your study is truly a randomized control trial it should say in the abstract and/or
the methods section of the article.
If it doesn't say then it is likely that the study is either descriptive non-experimental
or quasi-experimental.
You can tell the difference by looking into the methods section further.
Recall that if the intervention is missing the study is not an experiment.
As we just discussed, this type of research is observational in nature and therefore is
classified as a descriptive non-experimental study.
If there is no control group than the study is quasi-experimental.
A control group is a group of people that enter the study but do not receive the intervention
under study.
Instead, they are used for the purpose of comparison.
If the sample was not randomized properly or adequately or even at all then the study
is also quasi-experimental.
You may also see this type of study being called a non-randomized trial.
Many randomization strategies exist, but basically if a study is randomized it means that everyone
who entered the study had an equal chance of receiving the intervention under study.
You may see some studies indicate that they were partially randomized.
These studies still do not count as true experiments.
If your study has a random sample, control group and intervention than it is a randomized
control trial.
Sometimes I see students that are confused about the study design because of terms that
relate to the length of time the study was conducted or the sampling process.
While you are right that these terms relate to study designs they are not broad enough
to represent the methodology of the study and therefore do not give enough information
to the reader about the study design.
Terms like cross-sectional and longitudinal tell you how much time the study was conducted
over.
Cross sectional means that data were collected at one point in time.
Longitudinal means that data were collected over a long period of time.
These terms alone will not tell you if the study is descriptive non-experimental, quasi-experimental
or experimental.
If you use these words to describe your study design in the absence of one of the labels
we discussed in this video you will not have given your teacher enough information about
the study design to properly classify it.
Other confusing terms often relate to the way samples were collected, like convenience
sampling.
Convenience sampling means that the sample was readily available or accessible to the
researchers.
This term will give you the hint that the study does not have a random sample and is
therefore not a randomized controlled trial, but you still need to classify it further
as descriptive non-experimental or quasi-experimental.
To decide how to classify the design of a study you are looking at, follow the steps
outlined in this video.
Ask yourself the following three questions: Was there an intervention?
Is there a control group?
Was the sample random?
The answer to these questions will tell you how to classify the design of any quantitative
study into one of these three categories: descriptive non-experimental, quasi-experimental
or experimental.
Check with your teacher to see what other labels they may be expecting in the description
of your research design just in case they want more detail.
If you are looking for more detailed information you are welcome to check out my eBook or related
videos.
The eBook is best in PDF format, but is also available in other formats at the links below
this video.
If there is anything else you need please comment to let me know and subscribe so you
can keep up to date with videos as they are released.
Thank You.