Histogram (Uniform Widths)
What is a Histogram?
A histogram is a vertical bar chart in which the frequency corresponding to a class is represented by the area of a bar (or rectangle) whose base is the class width.
Note that the histogram differs from a bar chart in that it is the area of the bar that denotes the value, not the height. However, if the widths of the bars are uniform then only the height need to be considered.
In this lesson, we will look at histograms with uniform (equal width).
In another lesson, we will look at histograms with non-uniform widths
In a histogram:
There are no gaps between the rectangles
The y-axis is the frequency and always starts at 0.
Example
The following table shows the frequency distribution of the masses, in kg, of 21 members of a sports club.
Mass (kg) |
53 – 55 |
56 – 58 |
59 – 61 |
62 – 64 |
65 – 67 |
Frequency |
2 |
6 |
8 |
4 |
1 |
A histogram of the above frequency table is as follows:
Define a histogram.
Interpret a histogram.
Create a histogram from data.
A histogram is a bar graph that represents a frequency distribution. The width represents the interval and the height represents the corresponding frequency. There are no spaces between the bars.
Example:
Create a histogram from the following data:
Average Gas Mileage: 24,17,14,22,25,26,38,42,24,12,28,19,32,21,35,28,21,31,18,19
If there are no breaks in the data, then normally the last data value of a bin is the first value in the next bin.
Histogram Explained
This video will show you step by step on how to create a histogram from data.
Properties of Histograms
1. Quantitative Data
2. No gaps
3. Bar Width (Bin size or Class size)
4. Y-axis corresponds to the frequency
Example:
Here are the grades of 15 students
88,48,60,51,57,85,69,75,97,72,71,79,65,63,73
Build a histogram from the data.
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