420Hw08 - STAT 420 (10 points) (due Friday, October 26, by...

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STAT 420 Fall 2007 Homework #8 (10 points) (due Friday, October 26, by 3:00 p.m.) 1. A forester seeking information on basic tree dimensions obtains the following measurements of the diameters 4.5 feet above the ground and the heights of 12 sugar maple trees. The forester wishes to determine if the diameter measurements can be used to predict the tree height. Diameter x (inches) 0.9 1.2 2.9 3.1 3.3 3.9 4.3 6.2 9.6 12.6 16.1 25.8 Height y (feet) 18 26 32 36 44.5 35.6 40.5 57.5 67.3 84 67 87.5 a) Make a scatterplot of x vs. y . Does a straight-line relationship seem appropriate? b) Make a scatterplot of x ' = ln x vs. y ' = ln y . Does a straight-line relationship seem appropriate? c) Fit a straight-line regression to the transformed data. Add the least-squares regression line to the scatterplot from part(b). Comment on the adequacy of the fit. d) Construct a 95% prediction interval for the height of the tree y with the diameter x = 10 inches. Hint: Construct a 95% prediction interval for
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This note was uploaded on 04/29/2010 for the course STAT stat 420 taught by Professor Stepanov during the Spring '07 term at University of Illinois at Urbana–Champaign.

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420Hw08 - STAT 420 (10 points) (due Friday, October 26, by...

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