Deck 3: Descriptive Statistics: Numerical Measures

Question 1

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

Answer 1

A

Question 2

Since the population is always larger than the sample,the value of the sample mean

A)is always smaller than the true value of the population mean
B)is always larger than the true value of the population mean
C)is always equal to the true value of the population mean
D)could be larger,equal to,or smaller than the true value of the population mean

Answer 2

D

Question 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

Answer 3

C

Question 4

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

Question 5

The 75th percentile is referred to as the

A)first quartile
B)second quartile
C)third quartile
D)fourth quartile

Question 6

The most important statistical descriptive measure of the location of a data set is the

A)mean
B)median
C)mode
D)variance

Question 7

The mean of the sample

A)is always smaller than the mean of the population from which the sample was taken
B)can never be zero
C)can never be negative
D)None of these alternatives is correct.

Question 8

The mean of a sample

A)is always equal to the mean of the population
B)is always smaller than the mean of the population
C)is computed by summing the data values and dividing the sum by (n - 1)
D)is computed by summing all the data values and dividing the sum by the number of items

Question 9

The hourly wages of a sample of 130 system analysts are given below.

The coefficient of variation equals

A)0.30%
B)30%
C)5.4%
D)54%

Question 10

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

Question 11

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.

Question 12

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

Question 13

The median of a sample will always equal the

A)mode
B)mean
C)50th percentile
D)all of the above answers are correct

Question 14

In computing the mean of a sample,the value of $\Sigma$ x_i is divided by

A)n
B)n - 1
C)n + 1
D)n - 2

Question 15

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

Question 16

The 50th percentile is the

A)mode
B)median
C)mean
D)third quartile

Question 17

The median is a measure of

A)relative dispersion
B)absolute dispersion
C)central location
D)relative location

Question 18

$\mu$ is an example of a

A)population parameter
B)sample statistic
C)population variance
D)mode

Question 19

When computing the mean of a set of values x_i,the value of $\Sigma$ x_i

A)can never be zero
B)can never be negative
C)must always be positive
D)can be any value

Question 20

Which of the following provides a measure of central location for the data?

A)standard deviation
B)mean
C)variance
D)range

Question 21

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

Question 22

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

Question 23

When computing the mean,the smallest value

A)can never be negative
B)can never be zero
C)can never be less than the mean
D)can be any value

Question 24

Which of the following is not a measure of central location?

A)mean
B)median
C)variance
D)mode

Question 25

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.

Question 26

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

Question 27

When the data are skewed to the right,the measure of Skewness will be

A)negative
B)zero
C)positive
D)one

Question 28

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

Question 29

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

Question 30

The difference between the largest and the smallest data values is the

A)variance
B)interquartile range
C)range
D)coefficient of variation

Question 31

The weights (in pounds)of a sample of 36 individuals were recorded and the following statistics were calculated.

The coefficient of variation equals

A)0.1125%
B)11.25%
C)203.12%
D)0.20312%

Question 32

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

Question 33

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

Question 34

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

Question 35

The standard deviation of a sample of 100 observations equals 64.The variance of the sample equals

A)8
B)10
C)6400
D)4,096

Question 36

The most frequently occurring value of a data set is called the

A)range
B)mode
C)mean
D)median

Question 37

The heights (in inches)of 25 individuals were recorded and the following statistics were calculated

The coefficient of variation equals

A)11.2%
B)1120%
C)0.4%
D)40%

Question 38

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

Question 39

The value which has half of the observations above it and half the observations below it is called the

A)range
B)median
C)mean
D)mode

Question 40

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

Question 41

The numerical value of the standard deviation can never be

A)larger than the variance
B)zero
C)negative
D)smaller than the variance

Question 42

Which of the following symbols represents the size of the population?

A) $\sigma$ ²
B) $\sigma$
C) $\mu$
D)N

Question 43

A numerical measure of linear association between two variables is the

A)variance
B)covariance
C)standard deviation
D)coefficient of variation

Question 44

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

Question 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

Question 46

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

Question 47

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

Question 48

Which of the following symbols represents the standard deviation of the population?

A) $\sigma$ ²
B) $\sigma$
C) $\mu$
D)

Question 49

The symbol $\sigma$ 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

Question 50

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

Question 51

Which of the following symbols represents the mean of the sample?

A) $\sigma$ ²
B) $\sigma$
C) $\mu$
D)

Question 52

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

Question 53

Which of the following symbols represents the size of the sample

A) $\sigma$ ²
B) $\sigma$
C)N
D)n

Question 54

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

Question 55

Which of the following symbols represents the variance of the population?

A) $\sigma$ ²
B) $\sigma$
C) $\mu$
D)

Question 56

The variance of the sample

A)can never be negative
B)can be negative
C)cannot be zero
D)cannot be less than one

Question 57

Which of the following symbols represents the mean of the population?

A) $\sigma$ ²
B) $\sigma$
C) $\mu$
D)

Question 58

The variance can never be

A)zero
B)larger than the standard deviation
C)negative
D)smaller than the standard deviation

Question 59

The symbol $\sigma$ 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

Question 60

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

Question 61

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.

Question 62

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

Question 63

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.

Question 64

A numerical measure of linear association between two variables is the

A)variance
B)coefficient of variation
C)correlation coefficient
D)standard deviation

Question 65

Which of the following is not a measure of dispersion?

A)mode
B)standard deviation
C)range
D)interquartile range

Question 66

Given the following information:
Standard deviation = 8
Coefficient of variation = 64%
The mean would then be

A)12.5
B)8
C)0.64
D)1.25

Question 67

If the coefficient of variation is 40% and the mean is 70,then the variance is

A)28
B)2800
C)1.75
D)784

Question 68

The standard deviation of a sample was reported to be 20.The report indicated that
= 7200.What has been the sample size?

A)16
B)17
C)18
D)19

Question 69

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

Question 70

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

Question 71

Exhibit 3-1
The following data show the number of hours worked by 200 statistics students.

Refer to Exhibit 3-1.The class width for this distribution

A)is 9
B)is 10
C)is 11
D)varies from class to class

Question 72

From a population of size 500,a random sample of 50 items is selected.The mode of the sample

A)must be 500
B)must be equal to the mode of population,if the sample is truly random
C)must be equal to the mean of the population,if the sample is truly random
D)can be larger,smaller or equal to the mode of the population

Question 73

The relative frequency of a class is computed by

A)dividing the midpoint of the class by the sample size
B)dividing the frequency of the class by the midpoint
C)dividing the sample size by the frequency of the class
D)dividing the frequency of the class by the sample size

Question 74

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

Question 75

A group of students had dinner at a local restaurant.The total bill for the dinner was $414.70.Each student paid his/her equal share of the bill,which was $18.85.How many student's were at the dinner?

A)4
B)415
C)19
D)22

Question 76

From a population of size 400,a random sample of 40 items is selected.The median of the sample

A)must be 200,since 400 divided by 2 is 200
B)must be 10,since 400 divided by 400 is 10
C)must be equal to the median of population,if the sample is truly random
D)None of these alternatives is correct.

Question 77

The coefficient of correlation ranges between

A)0 and 1
B)-1 and +1
C)minus infinity and plus infinity
D)1 and 100

Question 78

From a population of size 1,000,a random sample of 100 items is selected.The mean of the sample

A)must be 10 times smaller than the mean of the population
B)must be equal to the mean of the population,if the sample is truly random
C)must be 10 times larger than the mean of the population
D)can be larger,smaller or equal to the mean of the population

Question 79

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

Question 80

The variance of a sample was reported to be 144.The report indicated that
= 7200.What has been the sample size?

A)49
B)50
C)51
D)52