Histogram

TL;DR

Visualizes how data values are distributed across consecutive intervals (bins).
Bars show the frequency (count) of observations in each bin.
Useful for spotting patterns or trends in a dataset.

Definition

A histogram is a graphical representation of data that displays the frequency or number of observations within a specified range of values, called bins.

Explanation

To construct a histogram you:

Choose a range of values and divide it into consecutive intervals (bins).
Count the number of observations that fall within each bin.
Plot the bins along the x-axis and the frequency (number of observations) for each bin on the y-axis.
Represent each bin’s frequency as a bar; the height of the bar corresponds to the count for that bin.

A histogram therefore shows the distribution of the data and helps identify patterns or trends.

Examples

Heights example

For a group of people, suppose the chosen range of values is from 0 to 8 inches, with a bin size of 1 inch. Count the number of people whose height falls within each bin. For the first bin (0 to 1 inch) there may be no people; for the second bin (1 to 2 inches) there might be 3 people. Continue this process for each bin and plot the resulting frequencies as bars on the histogram (x-axis: bins, y-axis: frequency).

Grades example

For a class of 30 students, choose the range of values 0 to 100 with a bin size of 10. Count the number of students whose grade falls within each bin. For the first bin (0 to 10) there may be no students; for the second bin (10 to 20) there might be 2 students. Continue this process for each bin and plot the frequencies as bars on the histogram (x-axis: bins, y-axis: frequency).

Use cases

Showing the distribution of a variable.
Identifying patterns or trends within data.
General data analysis to gain insights into a dataset.

Bins
Frequency
Distribution
Range
x-axis
y-axis