Descriptive Statistics Numerical Ch2 (34-66)

34. The variance of a sample of 81 observations equals 64. The standard deviation of the sample equals a. 9. b. 4096. c. 8. d. 6561. c ANSWER: 35. When the data are skewed to the right, the measure of Skewness will be a. negative. b. zero. c. positive. d. one. c ANSWER: 36. 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 ANSWER: 37. Which of the following is not a measure of variability? a. The range b. The 50th percentile c. The standard deviation d. The interquartile range b ANSWER: 38. Which difficulty of range as a measure of variability is overcome by interquartile 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 ANSWER: 39. When n-1 is used in the denominator to compute variance, 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 ANSWER: 40. 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 ANSWER: 41. The measure of variability that is influenced most by extreme values is a. the variance. b. the standard deviation. c. the range. d. the interquartile range. c ANSWER: 42. 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 ANSWER: 43. The descriptive measure of variability 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 ANSWER: 44. 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 ANSWER: 45. 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 ANSWER: 46. The coefficient of variation is a. the same as the variance. b. the standard deviation divided by the mean times 100. c. the square of the standard deviation. d. the mean divided by the standard deviation. b ANSWER: 47. The variance can never be a. zero. b. larger than the standard deviation. c. negative. d. smaller than the standard deviation. c ANSWER: 48. 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 ANSWER: 49. Which of the following symbols represents the standard deviation of the population? a. σ2 b. σ c. μ d. ANSWER: b 50. Which of the following symbols represents the mean of the population? a. σ2 b. σ c. μ d. ANSWER: c 51. Which of the following symbols represents the variance of the population? a. σ2 b. σ c. μ d. ANSWER: a 52. Which of the following symbols represents the size of the population? a. σ2 b. σ c. μ d. N d ANSWER: 53. Which of the following symbols represents the mean of the sample? a. σ2 b. σ c. μ d. ANSWER: d 54. Which of the following symbols represents the size of the sample? a. σ2 b. σ c. N d. n d ANSWER: 55. The symbol σ 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 ANSWER: 56. The symbol σ2 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 ANSWER: 57. The variance of the sample a. can never be negative. b. can be negative. c. cannot be zero. d. cannot be less than one. a ANSWER: 58. The measure of dispersion which is not measured in the same units as the original data is the a. median. b. standard deviation. c. coefficient of determination. d. variance. d ANSWER: 59. A numerical measure of linear association between two variables is the a. variance. b. covariance. c. standard deviation. d. coefficient of variation. b ANSWER: 60. 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. ANSWER: d 61. The correlation coefficient ranges between a. 0 and 1. b. -1 and +1. c. minus infinity and plus infinity. d. 1 and 100. b ANSWER: 62. 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 ANSWER: 63. The value of the sum of the deviations from the mean, i.e., must always be a. less than the zero. b. negative. c. either positive or negative depending on whether the mean is negative or positive. d. zero. d ANSWER: 64. The numerical value of the variance a. is always larger than the numerical value of the standard deviation. b. is always smaller than the numerical value of the standard deviation. c. is negative if the mean is negative. d. can be larger or smaller than the numerical value of the standard deviation. d ANSWER: 65. Since the median is the middle value of a data set it a. must always be smaller than the mode. b. must always be larger than the mode. c. must always be smaller than the mean. d. none of these alternatives is correct. d ANSWER: 66. 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 ANSWER: