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STAT 420
Spring 2008
Homework #10
(10 points)
(due Friday, April 18, by 4:00 p.m.)
1.
One Way ANOVA. Exercise
14.4
.
Use the
infmort
data set where Y is
income
and the grouping variable is
region
(Asia, Europe, Americas and Africa).
a)
Draw a boxplot of income for each of the four regions.
b)
Compute the sample mean and sample variance for each of the regions.
c)
A visual inspection of the boxplots may lead us to conclude that the equal variance
assumption may not be satisfied and that some transformation may be needed.
Nevertheless, for the moment, let us fit the model
Y
i
=
μ
1
v
1
i
+
μ
2
v
2
i
+
μ
3
v
3
i
+
μ
4
v
4
i
+
ε
i
,
where
ε
i
’s are
iid N
(
0
,
σ
2
), and the indicator variables are
v
1
i
is 1 if the
i
th country is in Asia and 0 otherwise,
v
2
i
is 1 if the
i
th country is in Europe and 0 otherwise,
v
3
i
is 1 if the
i
th country is in the Americas and 0 otherwise,
v
4
i
is 1 if the
i
th country is in Africa and 0 otherwise.
Suppose that you want to test the hypothesis that all population means are identical,
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This note was uploaded on 02/10/2009 for the course STAT 420 taught by Professor Stepanov during the Spring '08 term at University of Illinois at Urbana–Champaign.
 Spring '08
 STEPANOV
 Statistics

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