STAT 420
Spring 2010
Homework #3
(12 points)
(due Friday, February 12, by 4:00 p.m.)
1.
a)
4.6
The American Car Company is interested in the average number of cars coming off
three assembly lines with obvious defects (determined by visual inspection).
The
number of defects per week for each of the assembly lines is recorded for several
weeks.
The data follow.
Assembly Line
1
2
3
49
61
55
67
48
50
68
57
64
73
66
56
61
44
53
47
58
49
Given the observations above, test for differences in the mean number of visually
defective cars coming off the assembly lines using the
F
test.
Use
α
= 0.10.
> Y = c(49,61,55,67,48, 50,68,57,64,73,66,56, 61,44,53,47,58,49)
> A = c( 1, 1, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2,
3, 3, 3, 3, 3, 3)
> summary(aov(glm(Y ~ factor(A))))
Df Sum Sq Mean Sq F value Pr(>F)
factor(A)
2
330.0
165.0
2.8846 0.0871 .
Residuals
15
858.0
57.2
---
Signif. codes:
0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
p-value = 0.0871 < 0.10.
Reject
H
0
:
μ
A
=
μ
B
=
μ
C
at
α
= 0.10.