What is a two way ANOVA?
A two-way ANOVA is used when you have two or more independent variables.
For example, you would use a one-way ANOVA if you wanted to determine the effects of different types of fertilizer on the number of fruits your lemon tree produces. Your independent variable is the fertilizer type.
You would use a two-way ANOVA if you wanted to determine the effects of different types of fertilizer and the frequency with which you water the tree on the number of fruits produced. Your two independent variables are 1) fertilizer type and 2) frequency tree is water.