Brain and body regression The line on the scatterplot from p

Brain and body: regression. The line on the scatterplot, from problem 1 above, is the least-squares regression line for predicting brain weight from body weight. Suppose that a new mammal species is discovered hidden in the rain forest with body weight 600 kilograms.

A. ) Predict the brain weight for this species

B.) The correlation between body weight and brain weight for the data plotted above (question #5) is r = 0.86. How well does body weight explain brain weight for mammals? Give a number to answer this question, and briefly explain what the number tells us.

Solution

The regression equation is missing, however, I will guide you to find the solution.

A. For X = 600, is regression equation is:

Y = a + b*X

Prediction = Y = a + b*600

B. As r = 0.86, r² = 0.86² = 0.7396.

73.96% of variation in body weight is explained by brain weight for mammals.

r² is the proportion of variation in Y, explained by the variation in X in the given regression model.