Multiphase sampling is one of the probability sampling techniques that usually consist of two or more of both probability and non-probability techniques in choosing the target sample
The researchers will going to use purposive sampling in the first step
On the other hand, the researchers will use cluster sampling technique, a probability sampling technique to randomize the population.
Simple randomization sampling can be done using fish bowl method to get the names of the participants that will be included into two groups; the experimental group and the control group.
Between-group design of experimental research. In this design of experiments, a between-group design is an experiment that has two or more groups of subjects each being tested by a different testing factor simultaneously.
The between-group design to measure the effect of colors on the participants’ memory using a control and experimental group.
Within-Subjects Designs
A within-subjects design is an experiment in which the same group of subjects serves in more than one treatment. Note that I’m using the word "treatment" to refer to levels of the independent variable, rather than "group". It’s probably always better to use the word "treatment", as opposed to group. The term "group" can be very misleading when you are using a within-subjects design because the same "group" of people is often in more than one treatment. As an example of a within-subjects design, let’s say that we are interested in the effect of different types of exercise on memory. We decide to use two treatments, aerobic exercise and anaerobic exercise. In the aerobic condition we will have participants run in place for five minutes, after which they will take a memory test. In the anaerobic condition we will have them lift weights for five minutes, after which they will take a different memory test of equivalent difficulty. Since we are using a within-subjects design we have all participants begin by