Stem and leaf display
A stem-and-leaf display can also be used to organize only quantitative data. What do we mean though by stem and leaf?
We can divide the number 56 into a stem and a leaf.
5 is the stem and 6 is the leaf.
How do we divide though the number 9 though into a stem and a leaf?
You can use 0 as the stem and 9 as the leaf since 09 is the same as 9.
To make a stem-and-a-leaf display, just make a vertical line and put all the stems on the left of the vertical line and all the leaves on the right of the vertical line.
Let’s use the table below to make a stem-and-leaf display.
The first step is to identify all the stems.
After a close examination, we see that the stems are 0, 1, 2, 3, 4, 5, 6, and 7
The next step is to put all the stems on the left of the vertical line. Notice that the stems are in ascending order from top to bottom.
To complete the display, just put the leaves on the right of the vertical line.
For example, using the raw data in the table above, going from left to right, and starting with the first line, there are seven numbers that have a stem of 2.
These are 20, 20, 21, 24, 28, 22, and 24.
The leaves are 0, 0, 1, 4, 8, 2, 4
Just put these leaves on the right of the vertical line and on the same line as 2 as shown below.
You can complete the stem-and-leaf display by doing just that for the other stems. You will end up with this display.
From the display, you can clearly see that the stem 1 has the highest frequency and the stem 0 has the lowest frequency.
When there are too many rows, we can condense a stem-and-leaf display by combining adjacent rows.
You could group the rows as 0-1, 2-3, 4-5, and 6-7
Notice the use of the asterisk (*) to separate each stem of a group.
Graphs of quantitative data
Shapes of histograms