Natural populations of the plant Arabidopsis halleri have two leaf types. Some individuals have hairy leaves and others lack these hairs (naked). A research team wanted to investigate whether the persistence of both leaf types was due to the fact that if either leaf type becomes more abundant than the other in the population, herbivores target it and reduce its abundance relative to the other leaf type. To test this idea, they created plots with mixtures of the two leaf types. In some plots, hairy plants were more abundant than naked plants (relative abundance treatment H>N). In the other plots, naked plants were more abundant than hairy plants (relative abundance treatment N>H). Relative abundance treatments were randomly assigned to the plots. They introduced one beetle herbivore to the plots and recorded the average amount of leaf area lost to the beetles.

1. What is the response variable?
2. How many factors are included in this study? Mention them and state what type of variable they are
3. Is this an experiment or an observational study? What type of study design was used?
4. Provide a word statement of a full linear model to fit to the data. Explain what each term means.
5. Interpret the interaction plot.

The interaction plot can be viewed as a PDF called "leaf_type.pdf" inside the "R_data" folder.