BTRY 601
Solutions, Homework #6
Fall 2005
Due Friday, 10/28/2005 before class
Name (
last name first
, upper case letters)______________________________
General Guidelines:
9
Write down your name above (use upper case letters)
9
Check your computer lab # in the table below.
9
Make sure to type your solutions.
9
Please use JMP for data analysis (as necessary) and only attach relevant
output to each question.
This cover page must be
stapled to each homework assignment you turn
in. It is the front page of your homework.
Please, check your lab section in the space provided below
(Column #1).
Lab #
Day
Time
Location
TA
1_____
Monday
07300845PM
WN160
Matthias Kormaksson
2_____
Monday
07300845PM
WN B60
Hong Gao
3 Canceled Tuesday
10101125AM
WN B60
4_____
Tuesday
08400955AM
WN B60
Elizabeth Schifano
5_____
Tuesday
02550410PM
WN B60
Michael Grabchak
6_____
Tuesday
02550410PM
RR 160
David Clement
7_____
Tuesday
07300845PM
WN 160
Michael Grabchak
8_____
Monday
03000415PM
RR 163
David Clement
Note:
Students’ solutions to a few selected questions are posted at
http://www.duxbury.com/statistics_d/
. A zipped file is available for
download. Students’ solutions are also posted on our course web site
and can be accessed by clicking on the Homework link.
Grading Sheet
Maximum Points
Obtained Points
100
1
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View Full DocumentBTRY 601
Solutions, Homework #6
Fall 2005
Do the following exercises from
An Introduction to Statistical Methods and Data
Analysis (Ott and Longnecker, 5
th
Edition, 2004)
.
Exercise 6.30, p. 306:
4 points
22
/2
0.05 / 2
2
2
Paired data,
;
0.05, z
1.96,
5
(1.96) (75)
Range=300
ˆ
300/ 4
75
864.36
865
(5)
d
d
z
nE
E
nn
α
σ
== =
=
⇒=
=⇒
=
=
Exercise 6.32, p. 306:
10 points
29
a.
:
0 versus
:
0.
4.95,
29,
2
(
4.95)
0.000029
0.000029
0.05
Reject
.
od
ad
o
HH
td
f p
P
t
pH
µµ
=≠
==
⇒
−
=
≥
=
−=
<
value
value
The mean difference in the final grades of the academically oriented and
nonacademic home environments is not equal to zero.
d
b. From the output provided the 95% confidence interval for
(2.230, 5.370).
µ
=
c. No information is provided to indicate whether or not the 30 twins were
randomly selected. Nor is it mentioned whether members of each pair of twins
were randomly assigned to the academic and nonacademic environments.
Randomization is needed to validate the independence assumption. The normal
probability plot of scores clearly indicates that the normality assumption is
satisfied as the data points fall near the straight line.
The conditions for using the
t
procedures are satisfied if the independence and
normality assumptions are both valid. Since normality holds, one would need to
check with the experimenters regarding the unsettled independence assumption.
d. Yes, pairing is important in controlling subject to subject variability. Based on
the independent twosample ttest results, it turns out that there is no evidence of
a difference between the two population means (pvalue = 0.24), whereas the
paired ttest is highly significant as seen in (a). The scatter plot of the data shows
a strong positive correlation between the scores pinpointing data dependence.
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 Fall '05
 WELLS,M.
 Normal Distribution, Reject Ho, C. Ho, WN B60 WN, B60 WN B60, Michael Grabchak David

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