This is Review for you to understand Bar Graphs

1. Review of Bar Graphs
Objectives
After completing this unit you should be able to:
● Identify the bar graph title.
● Identify labels for the bar graph axes.
● Identify information given by a designated bar
● Make statements about data trends from a bar graph.
What is a Bar Graph?
A bar graph is a visual display used to compare the amounts or frequency of occurrence of
different characteristics of data. This type of display allows us to:
● compare groups of data, and to
● make generalizations about the data quickly.
● to organize data and information of the amount of things or people.
● it is a survey to collect data from different characteristics.
Price of Corn versus Quantity Demanded
This unit will introduce basic bar
graphs, how to read bar graphs. An
example of a bar graph is given on
the right.
When reading a bar graph there are
several things we must pay attention
to: the graph title, two axes,
including axes labels and scale, and
the bars. Since bar graphs are used
to graph frequencies or amounts of
data in discrete groups, we will
need to determine which axis is the
grouped data axis, as well as what
the specific groups are, and which
is the frequency axis.
``

2. Graph title, scale, labels,bars,axes.
Group data axis, frequency,discrete.
The height of the bars are particularly important since they give us information about specific
data.
Parts of a Bar Graph
Now let's look at the components of a bar graph individually. There is a lot of information in
this section so you may wish to jot down some short notes to yourself.
● Graph Title­­The graph title gives
an overview of the information
being presented in the graph. The
title is given at the top of the graph.
● Axes and their labels­­Each
graph has two axes. The axes
labels tell us what information is
presented on each axis. One axis
represents data groups, the other
represents the amounts or
frequency of data groups.
● Grouped Data Axis­­The
grouped data axis is always at the
base of the bars. This axis
displays the type of data being
graphed.
●
Frequency Data Axis­­The frequency axis has a scale that is a measure of the
frequency or amounts of the different data groups.
● Axes Scale­­ Scale is the range of values being presented along the frequency axis.
● Bars­­The bars are rectangular blocks that can have their base at either vertical axis
or horizontal axis (as in this example). Each bar represents the data for one of the data
groups.
Now let's look more closely at how the elements of a bar graph help us get a handle on the
information presented in a graph. While there are several ways to do this, here we will
present one way to get an overview of a graph using the graph above.
● Graph Title­­provides an overview of the type of information given in the bar graph.
● For the bar graph given, the title indicates that we are looking at data on:
● Vertical axis­­This axis is the frequency axis and contains the quantity demanded
given in units of bushels.
● Grouped Data Axis­­Since the the grouped data axis is always at the base of the
bars, the grouped data axis is the horizontal axis. The axis label tells us that along the

3. horizontal grouped data axis we have the price per bushel, with each data group being
a different dollar amount from $1 to $5.
● Two important pieces of information we must determine are the:
○ type of data being counted, and
○ how the data is grouped.
● Frequency Data Axis­­The scale is the range of frequency values shown on the
graph. The span of values represented is determined by the lowest and greatest
values you wish to include on the graph.
When looking
at this axis,
look to see
where the
range begins
and ends, as
well as at the
interval
between tick
marks. For a
further
discussion on
scale, read
the section on
Scale.
● The vertical
axis is the
quantity
demanded
given in units
of bushels.
● In this case,
the frequency
scale goes
from 0 to 80,
and uses an
interval of
units of 10.
The frequency
of our data
groups range
●
●

4. over nearly
the entire
scale so we
are able to
get a good
picture of our
data.

7. Example

8. Given the graph at right, below, answer the following questions
1.