You would use stem-and-leaf plots
for the following reasons:
-
They are easy to make.
-
They are best with values greater than 25.
-
They retain the original data.
-
They have several variations:
Back-to-back
Spread out
Truncated or rounded
-
They allow easy identification of the largest and smallest
values, clusters, gaps and outliers.
This is how to make a stem-and-leaf plot:
-
Find the smallest and the largest values.
-
Determine the stems and write them vertically on the left.
-
Add the leaves.
-
Arrange the leaves in order from smallest to largest.
-
Make a legend.
Fat Content in Grams for
Fast Food
| Fat Content in Grams in Fast-Food Breakfasts |
Fat Content in Grams in Fast-Food Sandwiches |
| Breakfast meal |
39 |
Mega hamburger with cheese |
26 |
| Double bacon and egg English muffin |
23 |
Double hamburger with cheese |
24 |
| Bacon and egg English muffin |
18 |
Big burger |
21.5 |
| Pancakes with syrup |
16 |
Double cheeseburger |
21 |
| Hash browns |
15 |
Spicy chicken sandwich |
20 |
| Bacon roll |
14 |
Vegetable sandwich |
18 |
| Egg and English muffin |
12.5 |
Chicken sandwich |
17 |
| |
|
Cheeseburger |
12 |
| |
|
Hamburger |
7.5 |
Fat Content in
Grams in Fast-Food Breakfasts
| Stems |
Leaves |
| 1 |
2, 4, 5, 6, 8 |
| 2 |
3 |
| 3 |
6 |
A stem-and-leaf plot shows the shape
and distribution of data. In the legend, |2|3 means 23. A Double
Bacon Egg McMuffin has 23 grams of fat. The numbers 12, 14, 15,
16 and 18 are from the row with a stem of 1. It can be clearly seen
in the diagram above that the data clusters around this row. 2|3
Back-to-Back Stem-and-Leaf
Plots
If you are comparing two sets of
data, you can use a back-to-back stem-and-leaf plot.
Fat Content in Grams in
Fast Food
| Fat Content in Grams for Breakfasts |
Stems |
Fat Content in Grams for Sandwiches |
| |
0 |
7 |
| 8, 6, 5, 4, 2 |
1 |
2, 7, 8 |
| 3 |
2 |
0, 1, 1, 4, 6 |
| 6 |
3 |
|
In the Fat Content for Sandwiches column, |6|3 means 36. The three
represents the tens place (the stem) and the six represents the
units place (the leaf). A Big Breakfast has 36 grams of fat. In
the row with a stem of 1, the numbers are 12, 14, 15, 16 and 18.
This diagram clearly shows that there are data clusters around the
rows with stems of 1 and 2.
|
