Factorial design

You may recall having seen this in the Experiments module. Studies with only one factor (independent/experimental variable) are called single-factor designs. If there is more than one factor (independent/experimental variable), then the design is termed factorial - multiple factors.

Single-factor study: Comparing high and low motivated subjects on some task

Design	Factor	Levels	Statistical analysis
Single-factor	A MOTIVATION	a1 High a2 Low	one-way ANOVA, 2 levels

Adding a second factor - GPA levels (Above 3.5, 2.0 to 3.5, below 2.0)

Design	Factor	Levels	Statistical analysis
Two-factor	A MOTIVATION	a1 High a2 Low	two-way ANOVA (2x3) - the 2x3 refers to respective levels of the independent variable (treatment)
	B GPA	b1 Above 3.5 b2 2.0-3.5 b3 Below 2.0

Adding a third factor - GENDER (Male and Female)

Design	Factor	Levels	Statistical analysis
Three-factor	A MOTIVATION	a1 High a2 Low	three-way ANOVA (2x3x2)
	B GPA	b1 Above 3.5 b2 2.0-3.5 b3 Below 2.0
	C GENDER	c1 Male c2 Female

Interpretation becomes complicated beyond 3 factors.

Return to module