Question 1

A stem-and-leaf diagram is useful in that it gives an overall picture of where quantitative data are centered and how the data are dispersed from the center.

Accepted Answer

A stem-and-leaf diagram provides information on the shape, center, and spread of quantitative data, making it a useful tool for data analysis.

Question 2

In order to summarize qualitative data,a useful tool is a __________.
A) histogram
B) frequency distribution
C) stem-and-leaf diagram
D) All of the above

Accepted Answer

Histograms and stem-and-leaf diagrams are useful tools for summarizing quantitative data, but they are not as useful for summarizing qualitative data. Instead, a frequency distribution is the best choice for summarizing qualitative data.

Question 3

A bar chart may be displayed horizontally.

Accepted Answer

A bar chart can be displayed either vertically or horizontally, depending on the preference of the presenter or the data being shown.

Question 4

Scatterplot is a graphical tool that is focused on describing one variable.

Accepted Answer

Scatterplot is a graphical tool that is used to describe the relationship between two variables.

Question 5

A polygon connects a series of neighboring points where each point represents the midpoint of a particular class and its associated frequency or relative frequency.

Accepted Answer

This statement accurately describes the concept of a frequency polygon, which is a graph that connects the midpoints of class intervals with their corresponding frequencies or relative frequencies.

Question 6

A bar chart depicts the frequency or relative frequency of each category of qualitative data as a bar rising vertically from the horizontal axis.It is also acceptable for the bar to extend horizontally from the vertical axis.

Accepted Answer

A bar chart can have bars that rise vertically or extend horizontally from the vertical axis.

Question 7

To approximate the width of a class in the creation of a bar chart,we may use this formula:

Accepted Answer

The formula mentioned in the statement is not given. Hence, it is not possible to determine if the statement is true or false.

Question 8

An ogive is a graph that plots the cumulative frequency (or the cumulative relative frequency)of each class above the lower limit of the corresponding class.

Accepted Answer

The answer of An ogive is a graph that plots...

Question 9

When constructing a pie chart,only a few,the most frequent,categories must be included in the pie.

Accepted Answer

A pie chart should include all categories or data points in order to accurately represent the data. Only including the most frequent categories can lead to a distorted view of the overall distribution.

Question 10

The percent frequency of a category equals the frequency of the category multiplied by 100%.

Accepted Answer

The answer of The percent frequency of a category equals...

Question 11

A frequency distribution for qualitative data groups these data into classes called intervals and records the total number of observations in each class.

Accepted Answer

A frequency distribution for qualitative data groups these data into classes called categories or groups, not intervals, and records the total number of observations in each category. Intervals are used for quantitative data.

Question 12

A pie chart is a segmented circle that portrays the categories and relative sizes of some quantitative variable.

Accepted Answer

The answer of A pie chart is a segmented circle...

Question 13

For quantitative data,a relative frequency distribution identifies the proportion of observations that fall into each class.

Accepted Answer

A relative frequency distribution shows the proportion or percentage of observations that fall into each class.

Question 14

A scatterplot is a graphical tool that helps determine whether or not two quantitative variables are related.

Accepted Answer

A scatterplot displays the correlation between two quantitative variables, allowing us to see if they are related and if so, the direction and strength of the relationship.

Question 15

When constructing a scatterplot for two quantitative variables,we usually refer to one variable as x and another one as y.Typically,we graph x on the vertical axis and y on the horizontal axis.

Accepted Answer

Typically, we graph x on the horizontal axis and y on the vertical axis.

Question 16

For quantitative data,a cumulative relative frequency distribution records the proportion (fraction)of values that fall below the upper limit of each class.

Accepted Answer

This is a correct statement describing the purpose of a cumulative relative frequency distribution.

Question 17

The relative frequency of a category is calculated by dividing the category's frequency by the total number of observations.

Accepted Answer

This statement is true. The relative frequency shows the proportion or percentage of observations that fall into a particular category out of the total number of observations. It is calculated by dividing the frequency of that category by the total number of observations in the data set.

Question 18

A histogram is a series of rectangles where the width and height of each rectangle represent the frequency (or relative frequency)and the width of the class,respectively.

Accepted Answer

In a histogram, the width of each rectangle represents the class interval, and the height represents the frequency (or relative frequency) of the data within that interval.

Question 19

Frequency distributions may be used to describe which of the following types of data?
A) Nominal and ordinal data only
B) Nominal and interval data only
C) Nominal,ordinal,and interval data only
D) Nominal,ordinal,interval,and ratio data

Accepted Answer

Frequency distributions can be used to describe all types of data: nominal, ordinal, interval, and ratio.

Question 20

When summarizing quantitative data it is always better to have up to 30 classes in a frequency distribution.

Accepted Answer

It is not always better to have up to 30 classes in a frequency distribution. The optimal number of classes will depend on the range of the data, the size of the dataset, and the purpose of the analysis. In general, too few classes may result in loss of important information, while too many may create noise and make it difficult to interpret the data. The choice of the number of classes should be based on statistical methods, such as Sturges' Rule or Scott's Rule, which take into account the sample size and the variability of the data.

Quiz 2: Tabular and Graphical Methods