Ch. 12 Definitions - Experiments with More than One Independent Variable

Interaction effect 

A result from a factorial design in which the difference in the levels of one independent variable changes, depending on the level of the other independent variable; a difference in differences 

Factorial design 

A study in which there are two or more independent variables, or factors

Cell

A condition in an experiment; in a factorial design represents one of the possible combinations of two independent variables

Participant variable

A variable such as age, gender, or ethnicity whose levels are selected, not manipulated

Main effect

In a factorial design, the overall effect of one independent variable on the dependent variable, averaging over the levels of the other independent variable 

Marginal means

In a factorial design, the arithmetic means for each level of an independent variable, averaging over the levels of another independent variable