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Homework Problems—These should be done individually!
Please note that HW problems generally do not require SAS coding.
#1.
(7 points) KKMN Problem 10.07.
Ignore the questions in the text and answer the following:
a.
Compute and interpret
2
1
2

Y X X
r
Also perform a hypothesis test to determine whether X2
should be included in a model containing X1.
b.
Compute and interpret
3
2
1
2

Y X X X
r
.
Also, perform the corresponding added variable test for X3
given X1 and X2.
c.
Compute and interpret
2
3
1
2

Y X X X
r
.
d.
Based on your previous results, suggest the most appropriate model.
#2.
(8 points) Consider the setting in problem KKMN 16.09.
Ignore the questions in the text. Tables
containing Type I and II SS for various models are given below.
The total SS was 3554.
Squared
Squared
Partial
Partial
Variable
DF
Type I SS
Type II SS
Corr Type I
Corr Type II
X3
1
2635.95947
396.37480
0.74169
0.40273
X4
1
229.80627
86.00677
0.25032
0.12764
X1
1
56.95559
55.45422
0.08275
0.08620
X2
1
43.45297
43.45297
0.06883
0.06883
Squared
Squared
Partial
Partial
Variable
DF
Type I SS
Type II SS
Corr Type I
Corr Type II
X3
1
2635.95947
396.37480
0.74169
0.40273
X1
1
231.86141
55.45422
0.25256
0.08620
X2
1
12.34665
43.45297
0.01799
0.06883
X4
1
86.00677
86.00677
0.12764
0.12764
Compute and interpret each of the following:
2
2
2
2
2
2
2
43
4123
134
213
1234
2413
143
,
,
,
,
,
,
Y
Y
Y
Y
Y
Y
Y
r
r
r
r
r
r
r
.
Looking at all the values provided above, including those you calculated, what do you think will
be the best model?
#3.
(10 points) Consider the data described in problem #2.
Additional output is shown on the last two
pages of the assignment.
Please answer the following questions.
a.
Examine the studentized residuals.
Discuss anything of interest. Be sure to specify critical
values from table A8B.
b.
Consider the influence statistics and determine if any of the observations have a large
influence on the regression line estimates.
Again, specify critical values from tables A9 and
A10 as appropriate.
c.
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 Fall '08
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