ABSTRACT
In many psychological experiments we are not only interested in the effects of a single independent variable (IV) on the dependent variable (DV). Rather, we can be interested in the effects of two or more IVs. The main reason for wanting to do this is because we may hypothesise that the IVs work together in their effects: that is, that the IVs interact with each other. The present chapter gives full examples in which two IVs are involved and then describes how this can be extended to situations which entail more than two IVs.
