| Q1. If we are testing for the difference between the means of two (2) related populations with samples ofn1= 20 andn2= 20, the number of degrees of freedom is equal to a. 39. b. 38. c. 19. d. 18. Q2. Given the following information, calculate the degrees of freedom that should be used in the pooled-variancettest: s12= 4 andn1= 16 s22= 6 andn2= 25 a.df= 41 b.df= 39 c.df= 16 d.df= 25 Q3. 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 Q4. 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 Q5. The objective of Analysis of Variance (ANOVA) is to analyze differences among the group means. a. true b. false Q6. 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. Q7. If we are testing for the difference between the means of two (2) independent populations with samplesn1= 20 andn2= 20, the number of degrees of freedom is equal to a. 39. b. 38. c. 19. d. 18. Q8. The statistical distribution used for testing the difference between two population variances is the ___ distribution. a.t b. standardized normal c. binomial d.F Q9. 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 Q10. TheFtest used for testing the difference in two population variances is always a one-tailed test. a. true b. false Q11. Given the following information, calculatesp2, the pooled sample variance that should be used in the pooled-variancettest: s12= 4 andn1= 16 s22= 6 andn2= 25 a.sp2 = 6 b.sp2 = 5 c.sp2 = 5.23 d.sp2 = 4 Q12. 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 Q13. 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 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, 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 Q15. 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 Q16. 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. theZtest. b. the chi-square test. c. Both of the above. d. None of the above. Q17. In a 2 x c contingency table, there will be c - 1 degrees of freedom. a. true b. false Q18. When using the chi-square test for independence, one should be aware that expected frequencies that are too small will lead to too big a Type I error. a. true b. false Q19. 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 Q20. 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 Q21. A test for whether one proportion is higher than the other can be performed using the chi-square distribution. a. true b. false Q22. 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, at alpha =0.05 level of significance, what would be the decision rule? | <1 Year | <1-4 Year | <5-9 Year | | High | 6 | 9 | 9 | | Average | 9 | 19 | 23 | | Low | 7 | 8 | 10 | a. Reject H0if chi-square > 16.919 b. Reject H0if chi-square > 15.507 c. Reject H0if chi-square > 11.143 d. Reject H0if chi-square > 9.488 Q23. A test for the difference between two proportions can be performed using the chi-square distribution. a. true b. false Q24. In testing a hypothesis using the chi-squared test, theexpected 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. Q25. 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 |
