1
Lecture 6
Stat102
2012
•
Assessing the importance of having a
sloped regression line (Chapter 3.4)
–
R squared
–
ANOVA table
–
F-test
NOTE: Your book titles this section: “Assessing the fit of the regression
line”. But it’s not really about how well the regression line fits.
I
t’s
really about how much better a sloped line fits than does a horizontal
one.

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2
Example: College Contribution Rate
Data: For a sample of major American Colleges & Universities,
x
= student /faculty ratio
Y
= % of alumni who contribute to the institution
Giving Rate = 53.01 - 2.057 Stud/Fac Ratio
Darker pt is U of Penn. Which school do you think is at
Y
=68%?
Which one is at
x
= 23 and
Y
= 19%?
“
How well does the L-S
line fit the data?
”
NOTE: Really should say:
“
How much better does it fit than
does a horizontal line
?”
0
10
20
30
40
50
60
70
Alumni Giving Rate
5
10
15
20
25
Student/Faculty Ratio