The design is powerful to overcome subject characteristics effect, maturation, history,
mortality, subject attitude and regression effects because random assignment assumes that the subjects
who are different, effective characteristics on the dependent variable of the study are presented in the
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groups in equal probability. Therefore, all characteristics of the participants are also randomly
assigned into the groups (Fraenkel & Wallen, 2006). For the mortality effect, random assignment
assumes that loss of subjects in treatment groups also occurs in control groups. Moreover, randomly
chosen participants in the groups which are not exposed to mortality effect can be excluded to provide
comparable groups in the design. The design also provides opportunity to compare different locations
by making two different comparisons; the first comparison should be made for the two treatment
groups and the second comparison should be done for any difference between the treatment and
control groups that are video-recorded.