Homework Assignment III
The questions in this part are based on Chapters 11. Please read through my notes and relevant sections of the
book to answer the questions. Good luck!
Directions
:
Identify the correct alternative for the following questions. You can put a cross or a tick mark on the
chosen alternative.
Questions 14 are based on the following study :
A study conducted in 2007 analyzed whether people belonging to different ethnic groups differed with respect to
their political beliefs. We are only given the following incomplete contingency table.
Political Party Identiﬁcation
Ethnic Group
Democrat
Independent
Republican
Total
White
516
123
1249
Black
623
576
Hispanic
75
460
Total
295
1364
1. Complete the above table. (
There are 7 blanks to ﬁll up).
2. What will be the conditional distribution of party identiﬁcation for Hispanics?
a) (38.33%, 46.28%, 45%)
b) (45%, 16.3%, 38.7%)
c) (6.9%, 2.49%, 5.92%)
d) (45%, 16.3%, 25%).
3. The following incomplete table shows the population conditional percentage values for a few cells. Complete
the table in such a way that ethnicity is independent of political afﬁliation.
Political Party Identiﬁcation
Ethnic Group
Democrat
Independent
Republican
Total
White
100%
Black
40%
100%
Hispanic
49%
100%
Extra Credit Question
4. Based on Q.1, what would have been the conditional distribution of party identiﬁcation for Hispanics if
ethnicity was independent of political afﬁliation?
(Hint : Think about expected counts of the cells).
a) (44.79%, 9.82%, 40%)
b) (45%, 16.3%, 38.7%)
c) (6.9%, 2.49%, 5.92%)
d) (44.79%, 9.82%, 45.39%).
Questions 59 are based on the following study :
The following table refers to a study recently carried out by the Florida Transportation Bureau about the effect of
wearing seat belts on the seriousness of injury in automobile accidents.
1
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View Full DocumentType of Injury
Seat Belt
Serious
Minor
No
3925
18,674
Yes
2150
20,750
Extra Credit Question
5. Find the numerical value and the degrees of freedom of the Chi square test statistic for testing the hypotheses
of independence between degree of injury and seatbelt usage.
a)
χ
2
= 625
.
98;
df
= 2
b)
χ
2
= 25
.
65;
df
= 2
c)
χ
2
= 625
.
98;
df
= 1
c)
χ
2
= 67
.
58;
df
= 4
.
6. Based on the pvalue of the above chisquare statistic, what should be your conclusion?
a) Seatbelt usage and seriousness of injury are independent at
α
= 0
.
01
,
α
= 0
.
05
and
α
= 0
.
1
.
b) Seatbelt usage and seriousness of injury are dependent at
α
= 0
.
1
but not at
α
= 0
.
05
and
α
= 0
.
01
.
c) Seatbelt usage and seriousness of injury are dependent at
α
= 0
.
05
and
α
= 0
.
1
but not at
α
= 0
.
01
.
d) Seatbelt usage and seriousness of injury are dependent at
H
0
at
α
= 0
.
01
,
α
= 0
.
05
and
α
= 0
.
1
.
7. Suppose Mr. X is just learning Statistics and does not know anything about Chisquare test. Worse still, he gets
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 Spring '08
 Ripol
 Statistics, Statistical tests, Nonparametric statistics, Wilcoxon signedrank test, close friends

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