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Graded Assignment
Wildlife biologists can fairly accurately determine the length of
an alligator from aerial photographs or from a boat. Determining the
weight of an alligator from a distance is much more
difficult. Wildlife biologists in Florida captured 25 alligators in
order to collect data and to develop a model from which weight can be
predicted from length. The data set alligator.txt contains the resulting
25 measurements, the first variable is the alligator's weight (in pounds?) and the second is its length (in inches?).
Make histograms of the alligators' lengths and weights. Also determine the mean and median length and weight of the alligators.
Try the following two linear regression models: (i) x = length and
y = weight; (ii) x = log(length) and y = log(weight).
For each model, draw a regression plot (data points with fitted regression
line) and a scatter plot of residual vs. x, and report the
R-square value. Which model do you think is better? Why? Write an equation estimating weight explicitly as a function of length. If you used log(length) and log(weight) to determine your model, be sure your final model is an expression for weight, not for log(weight).
Write a Word document containing your graphs and your concise answers to all the questions above. Be sure your graphs have titles and clear axis labels and that the answers to the questions above are clearly stated. Be sure your name is on your paper along with your lab section. Try to keep it limited to one page, but if you must use two pages, staple them together. This is to be turned in on Friday, 10 September at the beginning of the lab section. You will have two lab periods to work on it: 27 August and 3 September. If you realize you will not have enough time to finish the assignment by then, you need to work on it outside of lab time.