Explain the differences among preexperimental, true experimental, quasi-experimental, and statistical designs

What will be an ideal response?

Preexperimental designs are characterized by an absence of randomization. These designs do not employ randomization procedures to control for extraneous factors. The distinguishing feature of the true experimental designs, as compared to preexperimental designs, is randomization. In true experimental designs, the researcher can randomly assign test units and treatments to experimental groups. Quasi-experimental designs result when the researcher is unable to achieve full manipulation of scheduling or allocation of treatments to test units but can still apply part of the apparatus of true experimentation. However, because full experimental control is lacking, the researcher must take into account the specific variables that are not controlled. Statistical designs consist of a series of basic experiments that allow for statistical control and analysis of external variables. In other words, several basic experiments are conducted simultaneously. The basic designs used in statistical designs include preexperimental, true experimental, and quasi-experimental. Statistical designs are classified on the basis of their characteristics and use. The important statistical designs include randomized block, Latin square, and factorial.