Research Design Notation
This notation is mostly used in the context of studies in which
interventions (treatments) are performed on some groups of subjects. For
simplicity, we deal only with the case of two or more groups.
Design 1. Post-test only randomized experiment
The R indicates a randomized assignment of each subject to a group.
The X indicates an intervention or treatment of some kind (such as being
given a drug). The O indicates measurement of the dependent variable. So
in this example, the subjects are randomly assigned to one of two
groups. One of these groups gets the treatment, and the other does not.
Then, after a certain amount of time, an outcome is measured for each
person in all groups.
Design 2. Pre-Post non-randomized quasi experiment
The N indicates a non-random assignment to a group.
As you can see, a baseline measurement is made of the dependent
variable in both groups, and then an intervention is applied to one
group. Then the dependent variable is measured again. We refer to
this as a quasi-experiment because of the lack of randomized
assignment to groups.
Design 3. Post-test only non-experiment
Here there is a treatment, and then an outcome
is measured. This is largely useless.
|
