In pre-experimental designs, either a single group of participants or multiple groups are observed after some intervention or treatment presumed to cause change. Although they do follow some basic steps used in experiments, pre-experimental designs either fail to include a pretest, a control or comparison group, or both; in addition, no randomization procedures are used to control for extraneous variables. Thus, they are considered “pre-,” indicating they are preparatory or prerequisite to true experimental designs. Pre-experimental designs represent the simplest form of research designs. Together with quasi-experimental designs and true experimental (also called randomized experimental) designs, they make the three basic categories of designs with an intervention. Each contains subdesigns with specific strengths and weaknesses.
Because the validity of pre-experimental designs is threatened by inadequate control ...
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