# Assignment 2

## Due: Monday Friday, October 9, 1998

1. From Chapter 2 in the textbook, #2.4 parts a and c, #2.10 parts a and b, #2.13 parts a, b, and c, #2.23 all parts (on part c, give the p-value instead of using a 0.01-level test), #2.38, #2.42

2. Also: Study the TREES data. This data comes with MINITAB in a MINITAB worksheet (It will also be found on the class web page.) From within MINITAB, select "Open worksheet" under the file menu. The worksheet "trees.MTW" should be in MINITAB data folder. There are three variables in this data:

diameter = diameter of the tree in inches 4.5 feet above the ground

height = height of tree in feet

volume = volume of tree in cubic feet

The goal is to select either diameter or height to predict volume.

a) Plot volume vs. diameter and volume vs. height. Regress volume on diameter; regress volume on height. Based on these plots and the regression output, which variable do you prefer to use to predict volume? Explain your answer in three or fewer sentences.

b) For your choice of predictor from part a, does there appear to be a linear association with volume? Justify your answer statistically.

c) Would your conclusion in part b change if volume were given in cubic yards or cubic inches rather than in cubic feet? Explain. (You may wish to try transforming volume to see what happens.)

3. Also, for class discussion (but not to turn in), #2.12