Statistics

1. Which of the following provides a measure of central location for the data? a. standard deviation b. mean c. variance d. range

b

12. The first quartile a. contains at least one third of the data elements b. is the same as the 25th percentile c. is the same as the 50th percentile d. is the same as the 75th percentile

b

16. The most frequently occurring value of a data set is called the a. range b. mode c. mean d. median

b

21. Which of the following is not a measure of dispersion? a. the range b. the 50th percentile c. the standard deviation d. the interquartile range

b

10. The pth percentile is a value such that at least p percent of the observations are a. less than or equal to this value b. less than this value c. more than or equal to this value d. more than this value

a

20. When data are positively skewed, the mean will usually be a. greater than the median b. smaller than the median c. equal to the median d. positive

a

23. If the variance of a data set is correctly computed with the formula using n - 1 in the denominator, which of the following is true? a. the data set is a sample b. the data set is a population c. the data set could be either a sample or a population d. the data set is from a census

a

24. In computing descriptive statistics from grouped data, a. data values are treated as if they occur at the midpoint of a class b. the grouped data result is more accurate than the ungrouped result c. the grouped data computations are used only when a population is being analyzed d. None of these alternatives is correct.

a

29. The most important statistical descriptive measure of the location of a data set is the a. mean b. median c. mode d. variance

a

4. is an example of a a. population parameter b. sample statistic c. population variance d. mode

a

42. The symbol 2 is used to represent a. the variance of the population b. the standard deviation of the sample c. the standard deviation of the population d. the variance of the sample

a

51. Which of the following is not a measure of dispersion? a. mode b. standard deviation c. range d. interqurtile range

a

26. When should measures of location and dispersion be computed from grouped data rather than from individual data values? a. as much as possible since computations are easier b. only when individual data values are unavailable c. whenever computer packages for descriptive statistics are unavailable d. only when the data are from a population

b

43. A numerical measure of linear association between two variables is the a. variance b. covariance c. standard deviation d. coefficient of variation

b

46. The coefficient of correlation ranges between a. 0 and 1 b. -1 and +1 c. minus infinity and plus infinity d. 1 and 100

b

5. The hourly wages of a sample of 130 system analysts are given below. mean = 60 range = 20 mode = 73 variance = 324 median = 74 The coefficient of variation equals a. 0.30% b. 30% c. 5.4% d. 54%

b

50. During a cold winter, the temperature stayed below zero for ten days (ranging from -20 to -5). The variance of the temperatures of the ten day period a. is negative since all the numbers are negative b. must be at least zero c. cannot be computed since all the numbers are negative d. can be either negative or positive

b

6. The variance of a sample of 169 observations equals 576. The standard deviation of the sample equals a. 13 b. 24 c. 576 d. 28,461

b

11. The difference between the largest and the smallest data values is the a. variance b. interquartile range c. range d. coefficient of variation

c

13. Which of the following is not a measure of central location? a. mean b. median c. variance d. mode

c

15. Which of the following is a measure of dispersion? a. percentiles b. quartiles c. interquartile range d. all of the above are measures of dispersion

c

19. When the data are skewed to the right, the measure of Skewness will be a. negative b. zero c. positive d. one

c

2. A numerical value used as a summary measure for a sample, such as sample mean, is known as a a. population parameter b. sample parameter c. sample statistic d. population mean

c

22. The interquartile range is used as a measure of variability to overcome what difficulty of the range? a. the sum of the range variances is zero b. the range is difficult to compute c. the range is influenced too much by extreme values d. the range is negative

c

25. The measure of dispersion that is influenced most by extreme values is a. the variance b. the standard deviation c. the range d. the interquartile range

c

3. Since the population size is always larger than the sample size, then the sample statistic a. can never be larger than the population parameter b. can never be equal to the population parameter c. can be smaller, larger, or equal to the population parameter d. can never be smaller than the population parameter

c

30. The numerical value of the standard deviation can never be a. larger than the variance b. zero c. negative d. smaller than the variance

c

31. The sample variance a. is always smaller than the true value of the population variance b. is always larger than the true value of the population variance c. could be smaller, equal to, or larger than the true value of the population variance d. can never be zero

c

32. The variance can never be a. zero b. larger than the standard deviation c. negative d. smaller than the standard deviation

c

41. The symbol is used to represent a. the variance of the population b. the standard deviation of the sample c. the standard deviation of the population d. the variance of the sample

c

45. A numerical measure of linear association between two variables is the a. variance b. coefficient of variation c. correlation coefficient d. standard deviation

c

47. The coefficient of correlation a. is the same as the coefficient of determination b. can be larger than 1 c. cannot be larger than 1 d. cannot be negative

c

48. When the smallest and largest percentage of items are removed from a data set and the mean is computed, the mean of the remaining data is a. the median b. the mode c. the trimmed mean d. any of the above

c

49. In a five number summary, which of the following is not used for data summarization? a. the smallest value b. the largest value c. the mean d. the 25th percentile

c

7. The median of a sample will always equal the a. mode b. mean c. 50th percentile d. all of the above answers are correct

c

8. The median is a measure of a. relative dispersion b. absolute dispersion c. central location d. relative location

c

9. The 75th percentile is referred to as the a. first quartile b. second quartile c. third quartile d. fourth quartile

c

14. If a data set has an even number of observations, the median a. cannot be determined b. is the average value of the two middle items c. must be equal to the mean d. is the average value of the two middle items when all items are arranged in ascending order

d

17. The interquartile range is a. the 50th percentile b. another name for the variance c. the difference between the largest and smallest values d. the difference between the third quartile and the first quartile

d

18. If index i (which is used to determine the location of the pth percentile) is not an integer, its value should be a. squared b. divided by (n - 1) c. rounded down d. rounded up

d

27. The descriptive measure of dispersion that is based on the concept of a deviation about the mean is a. the range b. the interquartile range c. the absolute value of the range d. the standard deviation

d

28. The measure of location which is the most likely to be influenced by extreme values in the data set is the a. range b. median c. mode d. mean

d

33. If two groups of numbers have the same mean, then a. their standard deviations must also be equal b. their medians must also be equal c. their modes must also be equal d. None of these alternatives is correct

d

34. The sum of deviations of the individual data elements from their mean is a. always greater than zero b. always less than zero c. sometimes greater than and sometimes less than zero, depending on the data elements d. always equal to zero

d

40. Which of the following symbols represents the size of the sample a. 2 b. c. N d. n

d

44. Positive values of covariance indicate a. a positive variance of the x values b. a positive variance of the y values c. the standard deviation is positive d. positive relation between the independent and the dependent variables

d

52. Since the mode is the most frequently occurring data value, it a. can never be larger than the mean b. is always larger than the median c. is always larger than the mean d. None of these alternatives is correct.

d