# Statistics Chapter 12 Solutions

**Topics:**Statistical hypothesis testing, Null hypothesis, Statistical significance

**Pages:**50 (9415 words)

**Published:**December 1, 2012

1. When testing for independence in a contingency table with 3 rows and 4 columns, there are ________ degrees of freedom. a) 5

b) 6

c) 7

d) 12

ANSWER:

b

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test of independence, degrees of freedom

2. If we use the [pic] method of analysis to test for the differences among 4 proportions, the degrees of freedom are equal to: a) 3.

b) 4.

c) 5.

d) 1.

ANSWER:

a

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test for difference in proportions, degrees of freedom

3. If we wish to determine whether there is evidence that the proportion of successes is higher in group 1 than in group 2, the appropriate test to use is a) the Z test.

b) the [pic]test.

c) both of the above

d) none of the above

ANSWER:

a

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test for difference in proportions

4. If we wish to determine whether there is evidence that the proportion of successes is the same in group 1 as in group 2, the appropriate test to use is a) the Z test.

b) the [pic]test.

c) both of the above

d) none of the above

ANSWER:

c

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test for difference in proportions

5. In testing a hypothesis using the [pic] test, the theoretical frequencies are based on the a) null hypothesis.

b) alternative hypothesis.

c) normal distribution.

d) none of the above.

ANSWER:

a

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test for difference in proportions, properties

TABLE 12-1

A study published in the American Journal of Public Health was conducted to determine whether the use of seat belts in motor vehicles depends on ethnic status in San Diego County. A sample of 792 children treated for injuries sustained from motor vehicle accidents was obtained, and each child was classified according to (1) ethnic status (Hispanic or non-Hispanic) and (2) seat belt usage (worn or not worn) during the accident. The number of children in each category is given in the table below.

| |Hispanic |Non-Hispanic | |Seat belts worn |31 |148 | |Seat belts not worn |283 |330 |

6. Referring to Table 12-1, which test would be used to properly analyze the data in this experiment? a) test for independence.

b) test for difference between proportions.

c) ANOVA F test for interaction in a 2 x 2 factorial design. d) test for goodness of fit.

ANSWER:

a

TYPE: MC DIFFICULTY: Moderate

KEYWORDS: chi-square test of independence

7. Referring to Table 12-1, the calculated test statistic is a) -0.9991.

b) -0.1368.

c) 48.1849.

d) 72.8063.

ANSWER:

c

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test of independence, test statistic

8. Referring to Table 12-1, at 5% level of significance, the critical value of the test statistic is a) 3.8415.

b) 5.9914.

c) 9.4877.

d) 13.2767.

ANSWER:

a

TYPE: MC DIFFICULTY: Easy

KEYWORDS: chi-square test of independence, critical value

9. Referring to Table 12-1, at 5% level of significance, there is sufficient evidence to conclude that the a) use of seat belts in motor vehicles is related to ethnic status in San Diego County. b) use of seat belts in motor vehicles depends on ethnic status in San Diego County. c) use of seat belts in motor vehicles is associated with ethnic status in San Diego County....

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