Three-Way ANOVA

Didn't Drew Barrymore offer to define this term for Letterman one night? Or maybe that was Jean-Claude on Friends.

Yes, this is 50% more ANOVA-ey than the two-way ANOVA. The ANOVA test is a statistical test we can use to gain evidence to support the claim that the change in one variable was due to another variable or to suggest that the change might have been due to random chance.

A three-way ANOVA test allows us to test three different variables to determine their effect on a fourth. The three-way ANOVA results can provide evidence to support that one, two, or all three variables contributed to changes in the fourth. As an example, let’s say Polly suspects her homemade fertilizer, her watering technique, and the soil additives all contribute to the growth of her plants.

She can run a three-way ANOVA on the data she collects for different amounts of fertilizer, different watering amounts, and different amounts of soil additives to see which might contribute most to the plant growth. Additionally, the three-way ANOVA can also help her determine if one or more are working together at different levels. For example, maybe the fertilizer is only effective for higher amounts of water or that the soil additives only effect change when fertilizer levels are also high.