Researchers in Canada recently investigated the impacts on birds from the increased use of wind turbines and loss of nesting habitat.35 A random sample of Canadian bird habitats was obtained, and the...

Researchers in Canada recently investigated the impacts on birds from the increased use of wind turbines and loss of nesting habitat.35 A random sample of Canadian bird habitats was obtained, and the estimated number of nests (y, per hectare) was recorded for each. In addition, the number of wind farms (x1), number of turbines (x2), and area of the habitat (x3, in ha) was also recorded.

There is some evidence to suggest that the variation in the size of penguin colonies is related to sea ice extent. Suppose a study was conducted to investigate the effect of sea ice extent and stormy weather on the size of penguin colonies along the west coast of the Antarctic Peninsula. Fifteen years were selected at random, and the data were recorded.