STAT 1124 – Section 2
Assignment 5
Due Wednesday, March 4, 2009
Model Answers
You can complete these questions by using Excel or Statgraphics.
1.
Question 5.26, Page 140.
Using Excel, we obtain the following scatterplot:
Exercise 5.26 Page 140
y = 0.527x + 27.635
R
2
= 0.3114
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Brother's Height
Siste's Height
a.
The correlation coefficient r = square root of 0.3114 and is positive. It is
equal to 0.558
The Leastsquare regression is y = 27.64 + 0.527x
b.
Tonya height = 27.64 + 0.527*70 = 64.53 inches
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Question 5.40, Page 145.
Using Excel, we obtain the following scatterplot:
Exercise 5.40, Page 145
y = 11.894x  1.2861
R
2
= 0.8391
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0123456
Stemps
Larvae
r = square root of 0.8391 and is positive = 0.916.
The decision point to test whether there is a statistically significant relationship
between the stumps and beetle larvae is 0.413. Since r > 0.413, we can conclude that
there is a statistically significant relationship between the stumps and beetle larvae.
We can say that the data support the “beavers benefits beetles” idea.
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 Summer '09
 michael
 Regression Analysis, Pearson productmoment correlation coefficient, Errors and residuals in statistics, beetle, beetle larvae

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