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1、a. drawn from normal populationsb. drawn from matched pairs experimentc. independentd. larger than 30 c3. The Wilcoxon rank sum test statistic T is approximately normally distributed whenever the sample sizes are larger than:a. 10b. 15c. 20d. 25 a4. A Wilcoxon rank sum test for comparing two populat

2、ions involves two independent samples of sizes 5 and 7. The alternative hypothesis is stated as: The location of population 1 is different from the location of population 2. The appropriate critical values at the 5% significance level are:a. 20 and 45b. 22 and 43c. 33 and 58d. 35 and 565. Consider t

3、he following two independent samples: Sample A: 16 17 19 22 47 Sample B: 27 31 34 37 40 The value of the test statistic for a left-tail Wilcoxon rank sum test is:a. 6b. 20c. 35d. 55 b6. A nonparametric method to compare two populations, when the samples are independent and the data are either ordina

4、l or interval, and where the normality requirement necessary to perform the parametric test is not satisfied, is the:a. Wilcoxon rank sum testb. sign testc. Wilcoxon signed rank sum testd. equal-variance t-test of 7. Statistical methods that require few assumptions, if any, about the population dist

5、ribution are known as:a. parametric techniquesb. nonparametric techniquesc. free agent techniquesd. All of the above 8. Which of the following statements about nonparametric tests is false?a. We can safely employ nonparametric tests even when we know nothing at all about the populations from which s

6、ample data are being drawnb. We can conduct nonparametric tests with nominal datac. We can conduct nonparametric tests with ordinal datad. We can only conduct nonparametric tests with data of a higher order than nominal or ordinal9. Which of the following statements is false?a. We can conduct nonpar

7、ametric tests even with nominal and ordinal datab. When parametric assumptions are valid and, therefore, either type of test could be used, nonparametric tests are less powerful than parametric testsc. Given sample size and specified significance level, the probability of a Type II error is larger f

8、or a nonparametric testd. Using a nonparametric test when we could employ a parametric test can be less efficient: A nonparametric test often tends to ignore available sample information-for example, by focusing only on the directions rather than the sizes of observed differences.10. Consider the fo

9、llowing two independent samples: 15 17 18 14 16 19 19 20 22 23 The value of the test statistic for a right-tail Wilcoxon rank sum test is:a. 3b. 7c. 11d. 4411. The nonparametric tests discussed in your book （Wilcoxon rank sum test, sign test, Wilcoxon signed rank sum test, Kruskal-Wallis test and Fr

10、iedman test） all require that the probability distributions be:a. identical except with respect to locationb. identical except with respect to spread （variance）c. identical except with respect to shape （distribution）d. different with respect to location, spread, and shape12. Statistical methods that

11、 require, among other assumptions, that the populations be normally distributed are known as:a. distribution-free techniquesc. parametric techniquesd. both （a） and （b） are correct13. In a Wilcoxon rank sum test, the two sample sizes are 4 and 6, and the value of the Wilcoxon test statistic is T = 20

12、. If the test is a two-tail and the level of significance is, then:a. the null hypothesis will be rejectedb. the null hypothesis will not be rejectedc. the alternative hypothesis will not be rejectedd. not enough information has been given to answer this question14. Comparing the output of strawberr

13、ies grown on plots using fertilizer A with that grown on otherwise identical plots using fertilizer B, in order to make a general assessment of relative fertilizer effectiveness, may well call for aa. Friedman testb. Kruskal-Wallis testc. Wilcoxon rank-sum testd. Spearman rank correlation test15. A

14、Wilcoxon rank sum test for comparing two populations involves two independent samples of sizes 15 and 20. The un-standardized test statistic （that is the rank sum） is T = 210. The value of the standardized test statistic z is:a. 14.0b. 10.5c. 6.0d. 2.016. The appropriate measure of central location

15、of ordinal data is the:a. meanb. medianc. mode17. You are performing the Wilcoxon rank-sum test. The 13th through 15th values in an ordered array of pooled sample data all equal $180 （while the 12th value is less and the 16th value is more）. The appropriate ranks for the three $180 values area. 13,

16、14, 15b. 14, 14, 14c. 12.5, 13, 14.5d. 12.5, 13, 1518. In a normal approximation to the Wilcoxon rank sum test, the standardized test statistic is calculated as z = 1.80. For a two- tail test, the p-value is:a. 0.0359b. 0.4641c. 0.2321d. 0.0718 ANSWER:19. Which of the following will never be a requi

17、red condition of a nonparametric test?a. Data are ordinalb. Data are intervalc. The samples are drawn from normally distributed populations d. The populations being compared are identical in spread and shape20. A nonparametric method that is equivalent to the Wilcoxon rank sum test is the:a. Wilcoxo

18、n signed rank sum testb. Friedman testc. Kruskal-Wallis testd. Mann-Whitney test21. Consider the following data set: 2.2, 2.3, 2.3, 2.5, 2.6, 2.7, 2.8, 2.8, 2.8, 2.9, 3.1, 3.2, and 3.5. The rank assigned to the three observations of value 2.8 is:c. 8d. 922. The Wilcoxon rank sum test （like most of t

19、he nonparametric tests presented in your book） actually tests to determine whether the population distributions have identical:a. locationsb. spreads （variances）c. shapes 23. Inferential procedures that are free from restrictive assumptions about the sampled populations are known asa. Distribution-f

20、ree tests（because no assumption about the nature of the population distribution is being made）.b. Distribution-free tests （because no assumption about the nature of the sampling distributions of test statistics is being made）.c. Parametric testsd. All of the above24. To use the Wilcoxon Rank Sum Tes

21、t as a test for location, we must assume that a. the obtained data are either ordinal or interval where the normality requirement necessary to perform the equal-variances t test of is unsatisfiedb. both samples are randomly and independently drawn from their respective populationsc. both underlying

22、populations from which the samples were drawn are equivalent in shape and dispersion25. Which of the following correctly describes the Wilcoxon rank-sum test?a. It is a nonparametric test based on two independent simple random samplesb. It is designed to determine whether the relative frequency dist

23、ributions of two statistical populations of continuous values are identical to or different from one anotherc. It is equivalent to a parametric t - test of the difference between two means.d. All of the above. ANSWER:26. The first step in a Wilcoxon rank sum test is to combine the data values in the

24、 two samples and assign a rank of 1 to the:a. smallest observationb. middle observationc. largest observationd. observation that occurs most frequentlyTRUE / FALSE QUESTIONS27. A parametric test is a hypothesis test that depends on certain specific assumptions about the probability distribution of p

25、opulation values or the sizes of population parameters. T28. Nonparametric tests are methods of inference that make no assumptions whatsoever about the nature of underlying population distributions or their parameters.29. A nonparametric test is one that makes no assumptions about the specific shape

26、 of the population from which a sample is drawn.30. Nonparametric procedures are often, and perhaps more accurately, called free-agent statistics. F31. A Wilcoxon rank sum test for comparing two independent samples involves two samples of sizes 6 and 9. The alternative hypothesis is that the locatio

27、n of population 1 is to the left of the location of population 2. Using a 0.05 significance level, the appropriate critical values are 31 and 65. 32. In a Wilcoxon rank sum test for independent samples, the two sample sizes are 4 and 6, and the value of the Wilcoxon test statistic is T = 25. If the

28、test is a two-tail and the level of significance is 0.05, then the null hypothesis will be rejected.33. A Wilcoxon rank sum test for comparing two populations involves two independent samples of sizes 15 and 20. If the value of un-standardized test statistic is T = 225, then the value of the standardized test statistic is z = 1.50.34. Statistical tests that are not very sensitive to errors in assumptions are called parametric tests.35. Nonparametric tests are often more efficient than parametric tests.36. The statistical methods discus