Six Species of Wood-Pecking Birds Are Known to Damage Homes

Six species of wood-pecking birds are known to damage homes. Woodpeckers areprotected by the Federal Migratory Bird Treaty Act, and homeowners must controlthem by nonlethal methods. Over a three-month period, investigators evaluated theuse of mirrors, artificial snakes, and artificial owls as woodpecker deterrents.Homeowners' yards were classified into 4 categories: (1) no trees; (2) lightly woodedyards; (3) wooded yards; and (4) heavily wooded yards. The homes were visited atleast 4 times to establish baseline damage rates (number of new holes per day) beforeusing any deterrent. Deterrents were randomly assigned to the homes in eachcategory and changes in the damage rate were recorded at the end of the experimentaltime period. The design used was a randomized block design.(a) What is the explanatory variable (factor) for this experiment?

b) What is the response variable for this experiment?
(c) After completing the study, someone suggested that amount of rainfall mightaffect woodpecker activity and that homes in areas that receive more rainfallmight show greater damage. Is this something that the investigator should beworried about?
If yes, explain why; if no, explain what aspect of the design of theexperiment eliminates this worry.