Deck 2: Descriptive Statistics I: Elementary Data Presentation and Description

Question 1

A descriptive measure that is NOT measured in the same units as the original data is the variance.

Answer 1

True

Question 2

Since the population size is always larger than the sample size, a sample statistic can never be larger than the population parameter.

Answer 2

False

Question 3

If a distribution has a shape that is positively skewed, this means that it has an elongated tail that extends in the right-hand direction.

Answer 3

True

Question 4

The descriptive measures (mean, variance, and standard deviation) will yield different values for a relative frequency distribution versus a frequency distribution, for the same data set.

Question 5

In a cumulative frequency distribution, we can show directly the number of data set members at or below any specified value.

Question 6

In a bar chart, the height of the vertical bar represents the x value.

Question 7

On the horizontal axis of a bar chart, one places the frequency or the relative frequency (but only one).

Question 8

The range is the difference between the smallest and largest values in the data set.

Question 9

The median identifies the data set center by establishing a value such that at least half the numbers in the data set are at or above that value and at least half the numbers are at or below.

Question 10

The relative frequency of a class is the proportion of the number of members in that class.

Question 11

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

Question 12

The sample variance has the value n in the denominator while the population variance has the value n-1 in the denominator.

Question 13

If there are an odd number of items in a data set, the median is the average of the values of the two middle items.

Question 14

In general, when a data set shows positive skewness, the mean will be smaller than the median; for negatively skewed data, the mean will be larger than the median.

Question 15

The mean serves to act as a balancing point for the data.

Question 16

The standard deviation is approximately the average distance between the individual values in the data set and the data set center (i.e., the mean).

Question 17

When calculating the median of an ordered data set with an odd number of items, the median is the value of the middle item.

Question 18

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

Question 19

In a frequency distribution, x represents the possible values and f(x) represents the counts or frequencies of those values.

Question 20

The mean absolute deviation (MAD) measures the average absolute distance of data points from the mean of the data set.

Question 21

Which of the following best describes the mean absolute deviation (MAD):

A)it is the average of the squared differences between each data value and the mean
B)it is the negative square root of the variance
C)it measures the average absolute difference of data points from the mean
D)it is divided by n - 1 if the data is from a population
E)none of the above

Question 22

Which of the following is an accurate interpretation of the standard deviation of a population?

A)The standard deviation represents the exact average distance of each observation to the mean.
B)The standard deviation represents the square root of the average squared distance of each observation to the mean.
C)The standard deviation represents the square root of the sum of the squared distance of each observation to the mean.
D)The standard deviation represents the average deviation of each observation from the mean.
E)The standard deviation calculation involves n-1 in the denominator.

Question 23

Summaries of data, which may be tabular, graphical, or numerical, are referred to as:

A)inferential statistics
B)descriptive statistics
C)statistical inference
D)report generation
E)none of the above

Question 24

The main difference between a bar graph and a histogram is that the bars are separated in a histogram to emphasize the fact that each class is a separate category.

Question 25

Which of the following descriptive measures of dispersion is NOT in the same units as the original data?

A)range
B)mean absolute deviation
C)variance
D)standard deviation
E)none of the above

Question 26

In computing descriptive statistics from grouped data, the midpoint of each interval is treated as a representative value for all of the group members.

Question 27

The standard deviation of a sample:

A)is always smaller than the mean of the sample.
B)is always greater than the mean of the sample.
C)is always smaller than the variance of the sample.
D)is always greater than the variance of the sample.
E)none of the above.

Question 28

For a sample of 10 days, Harkin Research recorded the number of visitors to Tilton.com's website. 100, 100, 106, 93, 89, 95, 97, 181, 99, 100
Which measure of central tendency would seem to best represent the "typical" time that the rep spent with a client?

A)median
B)variance
C)standard deviation
D)mean
E)mode

Question 29

The point for which at least half the values in a data set are at or above the point and at least half the numbers are at or below the point is called the:

A)mode
B)peak
C)mean
D)median
E)average

Question 30

When looking at the shape of a distribution, which of the following best describes positive skewness?

A)the distribution is evenly split into two identical halves
B)the distribution has an elongated tail in the right-hand direction
C)the distribution has an elongated tail in the left-hand direction
D)the distribution has a very steep single peak
E)the distribution has two separate peaks with a valley in between

Question 31

The mean of a sample:

A)cannot exceed the variance of the data set
B)cannot exceed the standard deviation of the data set
C)is determined by adding up all of the values and dividing by the number of observations
D)is determined by adding up all of the values and dividing by the number of observations minus 1.
E)will be equal to the median

Question 32

Which of the following distribution shapes is one in which the distribution is split into two identical halves?

A)positively skewed
B)negatively skewed
C)symmetric
D)bimodal
E)flat

Question 33

In a data set with an odd number of observations, n,:

A)the median will be one of the values contained in the data set.
B)the median will be the average of the two central values.
C)the median is the (n-1)/2 nd observation
D)the median represents the "balance point" of the observations.
E)the median will be equal to the mode

Question 34

When working with grouped data, classes should touch but not overlap and classes should be of equal widths.

Question 35

If a data set has an even number of observations, then the median:

A)is the value of the middle item
B)is the average of the values for the middle two items when all of the items are arranged in ascending order
C)must be equal to the mean
D)is equal to the mode
E)none of the above

Question 36

If two groups of numbers have the same mean, then their:

A)standard deviations must also be equal
B)medians must also be equal
C)modes must also be equal
D)variances must also be equal
E)none of the above

Question 37

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
E)none of the above

Question 38

A frequency distribution is:

A)a tabular summary of a set of data showing the fraction of items in each of several non-overlapping classes
B)a graphical form of representing data
C)a graphical device for presenting qualitative data
D)a tabular summary of a set of data showing the number of items in each of several non-overlapping classes
E)none of the above

Question 39

The main difference between a bar chart and a histogram is that the bars are separated in a bar chart to emphasize the fact that each class/value is a separate category/discrete value.

Question 40

If the standard deviation of a data set is 0,

A)the data set is symmetric, and the negative values cancelled out the positive values.
B)the mean of the data set must also be 0.
C)a calculation error must have been made, as the standard deviation cannot be 0 when the data set has positive values.
D)all of the observations in the data set must be the same.
E)none of the above.

Question 41

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
E)none of the above

Question 42

On a recent biology quiz, about 90 percent of students earned excellent scores, but the other 10 percent did very poorly.The shape of the distribution of quiz scores is best described as:

A)symmetric
B)positively skewed
C)negatively skewed
D)steeply peaked
E)bimodal

Question 43

When working with grouped data, an approximate class width can be calculated as .

A)smallest value minus largest value divided by sample size
B)largest value minus smallest value divided by the number of classes
C)the number of classes divided by the range
D)the range divided by the actual class width
E)largest value plus smallest value divided by the number of classes

Question 44

The is the measure of central tendency that is most affected by very large or very small data values.

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

Question 45

A tabular summary of a set of data showing the proportion of the total number of items in several non-overlapping classes is a:

A)frequency distribution
B)relative frequency distribution
C)skewed frequency distribution
D)cumulative frequency distribution
E)none of the above

Question 46

In a relative frequency distribution, is substituted for the absolute count f(x) in each class.

A)a relative count P(x)
B)a cumulative count
C)a single count
D)the midpoint
E)the sample size

Question 47

When calculating the mean for grouped data, which of the following is used for the weights in the formula:

A)midpoint of each class
B)the class frequencies
C)the upper limit of each class
D)the bin range
E)none of the above

Question 48

The degree to which a data distribution has one extended "tail" showing either unusually large or unusually small values is called:

A)kurtosis
B)peakedness
C)skewness
D)symmetry
E)unimodal

Question 49

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
E)none of the above

Question 50

A data display that shows the number of data set members that are at or below a particular value or the number of data set members that are at or above a particular value is called a ___________ distribution.

A)unimodal
B)symmetric
C)positively skewed
D)cumulative
E)negatively skewed

Question 51

The is the measure of dispersion that is NOT expressed in the same units as the mean.

A)range
B)mean absolute deviation
C)variance
D)standard deviation
E)interquartile range

Question 52

A data set consists of 10 values: 9, 6, 2, 0, 2, 3, 5, 2, 1, 5.Determine the mean.

A)4.0
B)3.75
C)2.5
D)3.5
E)3.0

Question 53

In a bar chart, is indicated by an elongated tail in the left-hand direction.

A)positive skewness
B)negative skewness
C)symmetry
D)kurtosis
E)bi-modal

Question 54

Which of the following graphical presentations for depicting quantitative data has no natural separation between rectangles of adjacent classes:

A)bar chart
B)pie chart
C)histogram
D)box-and-whisker plot
E)scatter diagram

Question 55

A data set consists of 10 values: 9, 6, 2, 0, 2, 3, 5, 2, 1, 5.Determine the median.

A)3.75
B)3.5
C)4.0
D)3.0
E)2.5

Question 56

Which of the following best describes a histogram?

A)it is a bar chart used to show the relative frequency of qualitative data
B)it is commonly used to graphically present quantitative data
C)it is a bar chart that has no natural separation between the adjacent classes
D)b and c
E)all of the above

Question 57

The degree of steepness or peakedness in graph of a frequency or relative frequency distribution is called:

A)modality
B)kurtosis
C)skewness
D)dispersion
E)variation

Question 58

The total number of data items with a value less than or equal to the upper limit for the class is given by the:

A)frequency distribution
B)relative frequency distribution
C)cumulative frequency distribution
D)cumulative relative frequency distribution
E)none of the above

Question 59

When 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)all of the above
E)none of the above

Question 60

The term ______ describes the shape of a distribution of values when the distribution has two peaks.

A)skewed
B)symmetric
C)negatively adjusted
D)bimodal
E)positively skewed

Question 61

The number of US solar energy companies that applied for special tax credits in each of the past 11 months, according to a recent study, is shown below.Determine the median for the data. 14, 17, 12, 11, 17, 20, 11, 12, 15, 17, 20

A)14.5
B)16.0
C)14.0
D)15.5
E)15.0

Question 62

The table shows the life expectancy in years of the G8 countries (Datablog, Guardian.co.uk, July 8 2009).What is the mean life expectancy of the eight countries?

A)78.0
B)80.5
C)81.0
D)75.0
E)860.0

Question 63

The table shows the GDP per capita (in US $s) of the G8 countries (Datablog, Guardian.co.uk, July 8 2009).What is the mean GDP per capita of the eight countries?

A)$282,018
B)$35,252
C)$42,509
D)$40,288
E)$37,823

Question 64

The table shows the GDP per capita (in US $s) of the G8 countries (Datablog, Guardian.co.uk, July 8 2009).What is the median GDP per capita of the eight countries?

A)$282,018
B)$35,252
C)$42,509
D)$40,288
E)$37,823

Question 65

Below is a list of shipping costs quoted by six online retailers for the same item.Compute the MAD for the shipping cost data. $3.00 $2.84 $2.40 $3.02 $2.80 $2.51

A).235
B).312
C).204
D).164
E).238

Question 66

For a sample of 10 days, Harkin Research recorded the number of visitors to Tilton.com's website.Determine the median value for the data. 100, 100, 106, 93, 89, 95, 97, 181, 99, 100

A)100
B)121
C)99.5
D)106
E)115

Question 67

The table shows the life expectancy in years of the G8 countries (Datablog, Guardian.co.uk, July 8 2009).What is the median life expectancy of the eight countries?

A)78.0
B)80.5
C)81.0
D)75.0
E)860.0

Question 68

Below is a list of shipping costs quoted by six online retailers for the same item.Compute the variance of the shipping cost data.Treat the data as a population. $3.00 $2.84 $2.40 $3.02 $2.80 $2.51

A).033
B).241
C).137
D).054
E).015

Question 69

A data set contains only two values.The larger of the two values is 25.If the range is 12, what is the median value in the data set?

A)12
B)19
C)20
D)17
E)10

Question 70

For a sample of 10 days, Harkin Research recorded the number of visitors to Tilton.com's website.Compute the mean number of visitors per day. 100, 100, 106, 93, 89, 95, 97, 181, 99, 100

A)126
B)97
C)106
D)141
E)122

Question 71

Below is a list of shipping costs quoted by six online retailers for the same item.Compute the median shipping cost. $3.00 $2.84 $2.40 $3.02 $2.80 $2.51

A)2.82
B)2.76
C)1.56
D)2.80
E)3.5

Question 72

The number of US solar energy companies that applied for special tax credits in each of the past 11 months, according to a recent study, is shown below.Determine the mean for the data. 14, 17, 12, 11, 17, 20, 11, 12, 15, 17, 20

A)16.33
B)15.89
C)16.67
D)15.09
E)13.44

Question 73

The closing share price for G.E.stock over the past seven days is shown below.Compute the range for this data. 112, 115, 111, 116, 116, 116, 112

A)4
B)6
C)5
D)4.5
E)3

Question 74

Below is a list of shipping costs quoted by six online retailers for the same item.Compute the average shipping cost. $3.00 $2.84 $2.40 $3.02 $2.80 $2.51

A)1.43
B)1.98
C)2.76
D)2.61
E)2.38

Question 75

Below is a list of shipping costs quoted by six online retailers for the same item.Compute the standard deviation of the shipping cost data.Treat the data as a population. $3.00 $2.84 $2.40 $3.02 $2.80 $2.51

A).55
B).23
C).058
D).37
E).64

Question 76

A data set consists of 10 values: 9, 6, 2, 0, 2, 3, 5, 2, 1, 5.Determine the mode.

A)2
B)3
C)2.5
D)3.25
E)2.75

Question 77

For a sample of 10 days, Harkin Research recorded the number of visitors to Tilton.com's website.Determine the mode for the data. 100, 100, 106, 93, 89, 95, 97, 181, 99, 100

A)106
B)99.5
C)105.0
D)100
E)105.5

Question 78

The number of US solar energy companies that applied for special tax credits in each of the past 11 months, according to a recent study, is shown below.Determine the mode for the data. 14, 17, 12, 11, 17, 20, 11, 12, 15, 17, 20

A)12.5
B)16.5
C)16
D)11
E)17

Question 79

The table shows the life expectancy in years of the G8 countries (Datablog, Guardian.co.uk, July 8 2009).What is the mode of life expectancy in the eight countries?

A)78 years
B)80 years
C)81 years
D)75 years
E)860 years

Question 80

The closing share price for G.E.stock over the past seven days is shown below.Compute the MAD for the data. 112, 115, 111, 116, 116, 116, 112

A)2.0
B)3.5
C)2.5
D)3.0
E)1.75