what are the two main reasons to conduct a factorial study? a. to find moderators and to find mediators b. to increase internal validity and to establish external validity c. to test limits and to test theories d. to compare participant variables and to establish covariance

Generally, In the field of statistics, a factorial design study is one whose design consists of two or more factors, each of which has discrete possible values or "levels," and whose experimental units take on all possible permutations of these levels across all such factors.

A full factorial experiment may also be referred to as a multifactorial experiment.

When conducting a study using a factorial design, two or more intervention comparisons are carried out concurrently.

As an example, participants may be assigned at random to receive either aspirin or a placebo, as well as to receive either a behavioral intervention or regular medical treatment.