Q1. When testing for the difference between the variances of two population with sample sizes of n1 = 8 and n2 = 10, the number of degrees of freedom is (are):
a. 8 and 10.
b. 7 and 9.
c. 18.
d. 16.
Q2. The objective of Analysis of Variance (ANOVA) is to analyze differences among the group means.
a. true
b. false
Q3. Given the following information, calculate sp2, the pooled sample variance that should be used in the pooled-variance t test:
s12 = 4 and n1 = 16
s22 = 6 and n2 = 25
a. sp2 = 6
b. sp2 = 5
c. sp2 = 5.23
d. sp2 = 4
Q4. The use of preservatives by food processors has become a controversial issue. Suppose 2 preservatives are extensively tested and determined safe for use in meats. A processor wants to compare the preservatives for their effects on retarding spoilage. Suppose 15 cuts of fresh meat are treated with preservative A and 15 are treated with preservative B, and the number of hours until spoilage begins is recorded for each of the 30 cuts of meat. Referring to the Table below, state the F-test statistic for determining if the population variances differ for preservatives A and B.
|
Perservative A
|
Perservative B
|
|
XbarA = 106.4 hours
|
XbarB = 96.54 hours
|
|
SA = 10.3 hours
|
SB = 13.4 hours
|
a. F = - 3.10
b. F = 0.5908
c. F = 0.7687
d. F = 0.8250
Q5. A supermarket is interested in finding out wheather the mean weekly sales volume of Coca-Cola are the same when the softdrinks are displayed on the top shelf and when they are displayed on the bottom shelf. 10 stores are randomly selected from the supermaket chain with 5 stores using the top shelf display and 5 stores using the bottom shelf display. Assume that the samples are normally distributed with equal population variances. Refere to the sales volume data in the table below, Top shelf Sales Mean=41.6, Variance=249.84, Bottom shelf sales Mean=62.2, Variance=66.96.
What is the sample pooled variance Sp2?
|
Top Shelf Sales Volume
|
23
|
35
|
50
|
68
|
32
|
|
Bottom Shelf Sales Volume
|
55
|
70
|
72
|
51
|
63
|
a. 158.4
b. 11.995
c. 0
d. -11.995
Q6. If we are testing for the difference between the means of two (2) independent populations with samples n1 = 20 and n2 = 20, the number of degrees of freedom is equal to
a. 39.
b. 38.
c. 19.
d. 18.
Q7. In testing for the differences between the means of two related populations, we assume that the differences follow a _______ distribution.
a. normal
b. odd
c. sample
d. population
Q8. A supermarket is interested in finding out whether the mean weekly sales volume of Coca-Cola are the same when the soft drinks are displayed on the top shelf and when they are displayed on the bottom shelf. Ten stores are randomly selected from the supermarket chain with 5 stores using the top shelf display and 5 stores using the bottom shelf display. Assume that the samples are normally distributed with equal population variances. Refer to the sales volume data in the table below, What are the critical values using a level of significance alpha=.01?
|
Top Shelf Sales Volume
|
23
|
35
|
50
|
68
|
32
|
|
Bottom Shelf Sales Volume
|
55
|
70
|
72
|
51
|
63
|
a. +2.7638 and -2.7638
b. +2.8965 and -2.8965
c. +3.3554 and -3.3554
d. +4.5407 and -4.5407
Q9. In testing for the differences between the means of two related populations, the _______ hypothesis is the hypothesis of "no differences."
a. null
b. sample
c. experiment
d. first
Q10. A supermarket is interested in finding out whether the mean weekly sales volume of Coca-Cola are the same when the soft drinks are displayed on the top shelf and when they are displayed on the bottom shelf. 10 stores are randomly selected from the supermarket chain with 5 stores using the top shelf display and 5 stores using the bottom shelf display. Assume that the samples are normally distributed with equal population variances. Refer to the sales volume data in the table below, Top shelf Sales Mean=41.6, Variance=249.84, Bottom shelf sales Mean=62.2, Variance=66.96.
What is the t-test statistic?
|
Top Shelf Sales Volume
|
23
|
35
|
50
|
68
|
32
|
|
Bottom Shelf Sales Volume
|
55
|
70
|
72
|
51
|
63
|
a. -2.588
b. -9.405
c. 9.405
d. 2.13
Q11. In testing for the differences between the means of two independent populations, we assume that the 2 populations each follow a _______ distribution.
a. sample
b. normal
c. odd
d. experiment
Q12. The statistical distribution used for testing the difference between two population variances is the ___ distribution.
a. t
b. standardized normal
c. binomial
d. F
Q13. If we are testing for the difference between the means of two (2) related populations with samples of n1 = 20 and n2 = 20, the number of degrees of freedom is equal to
a. 39.
b. 38.
c. 19.
d. 18.
Q14. 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. Referring to the Table below, the calculated chi square test statistic is
|
Hispanic
|
Non-Hispanic
|
|
Seat belts worn
|
31
|
148
|
|
Seat belts not worn
|
283
|
330
|
a. -0.9991
b. -0.1368
c. 48.1849
d. 72.8063
Q15. In a 2 x c contingency table, there will be c - 1 degrees of freedom.
a. true
b. false
Q16. If we use the chi-square method of analysis to test for the difference between proportions, we must assume that there are at least 5 observed frequencies in each cell of the contingency table.
a. true
b. false
Q17. 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. Referring to the Table below, at 5% level of significance, the critical value of the test statistic is
|
Hispanic
|
Non-Hispanic
|
|
Seat belts worn
|
31
|
148
|
|
Seat belts not worn
|
283
|
330
|
a. 3.8415
b. 5.9914
c. 9.4877
d. 13.2767
Q18. If we use the chi-square 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
Q19. In testing a hypothesis using the chi-squared test, the expected frequencies are based on the
a. assumption the null hypothesis is true: the proportion of successes in the two populations are equal.
b. the null hypothesis is false: the proportion of successes in the two populations are not equal.
c. normal distribution. d. None of the above.
Q20. In testing the difference between two proportions using the normal distribution, we may use either a one-tailed Chi-square test or two-tailed Z test.
a. true
b. false
Q21. One criterion used to evaluate employees in the assembly section of a large factory is the number of defective pieces per 1,000 parts produced. The quality control department wants to find out whether there is a relationship between years of experience and defect rate. A defect rate in terms of High, Average or Low is calculated for each worker in a yearly evaluation. The results for 100 workers based on years of experiences are given in the table below.
Referring to the Table below, which test would be used to properly analyze the data in this experiment to determine whether there is a relationship between defect rate and years of experience?
|
<1 Year
|
<1-4 Year
|
<5-9 Year
|
|
High
|
6
|
9
|
9
|
|
Average
|
9
|
19
|
23
|
|
Low
|
7
|
8
|
10
|
a. chi-square test for independence
b. chi-square test for differences between two proportions (independent samples)
c. chi-square test for differences between two proportions (related samples)
d. chi-square test for differences among more than two proportions
Q22. A test for the difference between two proportions can be performed using the chi-square distribution.
a. true
b. false
Q23. 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. Referring to the Table below, which test would be used to properly analyze the data in this experiment?
|
Hispanic
|
Non-Hispanic
|
|
Seat belts worn
|
31
|
148
|
|
Seat belts not worn
|
283
|
330
|
a. chi-square test for independence
b. chi-square test for differences between two proportions (independent samples)
c. chi-square test for differences between two proportions (related samples)
d. chi-square test for differences among more than two proportions
Q24. The squared difference between the observed and theoretical frequencies should be large if there is no significant difference between the proportions.
a. true
b. false
Q25. The Marascuilo procedures allows one to make comparisons between all pairs of group to figure out which of the population proportions differ.
a. true
b. false