Description
Madgyal sheep is indigenous breed of sheep and distributed in Maharashtra state of India. Due to high
growth rate, this breed is of special importance for growth traits studies. A study records the body
weights (lbs) for 60 lambs and their age (month). A simple linear regression model was implemented to
analyze the relation between lamb weight and age. The results are shown below.
A. Do the simple linear regression model assumptions appear to be satisfied? Discuss each
assumption separately.
B. Regardless of your answer in A. Use the model results to build a 95% prediction interval for a 10-
month-old lamb. Use Sxx=719.345 and 𝑥̅=6.333
C. Regardless of your answer in A. Use the model results to build a 95% confidence interval for the
average weight of lambs that are 10-month-old. Which interval is wider?
D. Can you predict the weight for a 3-year-old lamb? Why or why not?
The analysis was re-run on the log transformed data. The new results are shown below. Use it to answer
the following questions E to G.
E. Do the simple linear regression model assumptions appear to be satisfied? Discuss each
assumption separately.
F. Discuss the advantage of the log transformation in terms of the linear regression model.
G. Run a hypothesis test to check if there is a significant linear relation between the log of lamb
weight and log of lamb age
