The following description of a statistical study is an excerpt from Understandable Statistics Concepts and Methods,…

The following description of a statistical study is an excerpt from Understandable Statistics Concepts and Methods, 10 Ed., by Brase and Brase. In 1778, Captain James Cook landed in what we now call the Hawaiian Islands. He gave the islanders a present of several goats, and over the years these animals multiplied into wild herds totaling several thousands. They eat almost anything, including the famous silver sword plant, which was once unique to Hawaii. At one time, the silver sword grew abundantly on the island of Maui … but each year there seemed to be fewer and ſewer plants. Biologists suspected that the goats were partially responsible for the decline in the number of plants and conducted a statistical study that verified their theory. d) What are the confounding variables this study attempts to control and how does the study attempt to control each?