A stem plot, or a stem and leaf plot, is a way to visually represent quantitative data. Stem plots work by breaking a number into two parts and stem and a leaf. The leaf portion of the number is the very last digit, while the stem portion is the rest of the number.
Take for example the following examples:
The number 12, the 1 is considered the stem and 2 is the leaf.
For the number 257, the 25 is considered the stem and 7 is the leaf.
If the number has a decimal in it, like 54.3, the 3 is the leaf and the 54 is the stem.
If the number has only one digit, such as 8, then the leaf is still 8, and the stem is 0 because in front of any number is 0.
To create a stem plot, let’s take the following dataset.
The first step in creating a stem plot is to determine the stems associated with this dataset. In this dataset the smallest number is 1, and the largest number is 33. So, the stems associated with this dataset would be 0, 1, 2, and 3. We write these numbers in numerical order vertically, with a vertical line to their right.
The first point in the dataset is 18. The stem for this number is 1 and the leaf is 8. So, we write an 8 next to the 1.
the next point is an 11. Both the stem and leaf for this number is 1. Since 1 is less then 8 we write the 1 before the 8 because we write the leaves in numerical order.
We continue this process until we have all of the numbers. A complete stem plot is as below
Stem plots are usefull in displaying quantitative data with low variability.