Introductory Graphing: Bar Graphs
Bar graphs:
Here is an example of a bar graph.
- Bar graphs are used to present and compare data.
- There are two main types of bar graphs: horizontal and vertical (we will focus on Vertical). They consist of rectangular bars that vary in height or length according to their value or frequency.
This is a Vertical bar graph.
- A Vertical bar graph consists of an x-axis, and y-axis.
- The numbers on the axes are known as the scales. Each bar represents a numeric or categorical variable.
- In the example above, the x-axis records the colors preferred, where as the y-axis represents the amount of people recorded that like said colors.
- Every bar graph should have a:
- Title (Students Who Worked Ages 14-18)
- Labelled x-axis (Ages) and y-axis (Number of Students)
- Neat and proportional columns
- Clearly identified structure (x-axis: 14, 15, 16 etc.. & y-axis: 0, 5, 10 etc.)
Group/double Bar Graphs:
- Double and group bar graphs are used to compare data about the same location or things.
- These graphs make it possible to compare several things at once but can be confusing if too much data is involved.
Here is a quick and accurate animated video on how to make a double bar graph.
Activity: Favorite Movie Types
Imagine yourself in a classroom of 35 students. You are to ask your classmates about their favorite movie types- in other words, you are to collect data.
Here is the information you have collected:
11 students prefer comedy.
7 students prefer horror.
5 students prefer action.
8 students prefer romance.
4 students prefer science-fiction.
In order to create our first bar graph, we will follow a few steps.
STEP 1: We must give a title to our graph - let us call it "Favorite Movie Types".
STEP 2: We must clearly title the x-axis and y-axis. Our x-axis will be "Movie Types" and our y-axis will be "Number of Students".
STEP 3: We must clearly label the x and y-axis according to the data collected.
STEP 4: We must neatly enter the data.
Here is the information you have collected:
11 students prefer comedy.
7 students prefer horror.
5 students prefer action.
8 students prefer romance.
4 students prefer science-fiction.
In order to create our first bar graph, we will follow a few steps.
STEP 1: We must give a title to our graph - let us call it "Favorite Movie Types".
STEP 2: We must clearly title the x-axis and y-axis. Our x-axis will be "Movie Types" and our y-axis will be "Number of Students".
STEP 3: We must clearly label the x and y-axis according to the data collected.
STEP 4: We must neatly enter the data.
Now let us use the data we collected to construct a Double Bar Graph depicting boy and girl preferences.
Here is the information you had collected:
11 students prefer comedy (6 boys and 5 girls)
7 students prefer horror (5 boys and 2 girls)
5 students prefer action (3 boys and 2 girls)
8 students prefer romance (3 boys and 6 girls)
4 students prefer science-fiction. (1 boy and 3 girls)
We will use the same steps as we previously did, although we must make sure to clearly identify the column representing the boys' preferences and the column depicting the girls' preferences.
Here is the information you had collected:
11 students prefer comedy (6 boys and 5 girls)
7 students prefer horror (5 boys and 2 girls)
5 students prefer action (3 boys and 2 girls)
8 students prefer romance (3 boys and 6 girls)
4 students prefer science-fiction. (1 boy and 3 girls)
We will use the same steps as we previously did, although we must make sure to clearly identify the column representing the boys' preferences and the column depicting the girls' preferences.