So far all of our analyses have asked questions about the manipulation of a single independent variable. The t-test can compare two groups/levels while the ANOVA can ask about the differences between multiple levels. But, what do we do when there is more than one independent variable being manipulated within our experiment? What if we want to know how these factors interact with each other to produce our final result? To demonstrate how you could assess these questions we’ll again go through our Cholesterol.csv dataset.