Designs involving between 2 and 8 quantitative factors, each of which is set at an arbitrary number of levels. Among the uses of this design is providing candidate runs for augmenting undesigned experiments where the experimenter may take previous test data generated in a non-structured manner and incorporate them into a formal experimental design.

In a factorial design the researcher can maipulate TWO OR MORE independent variables and measure their effects on an idependent variable. Factorial designs may be experimental, nonexperimental, quasi-experimental or mixed.