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### Course: Statistics and probability>Unit 2

Lesson 1: Displaying quantitative data with graphs

# Stem and leaf plots review

## Stem and leaf plots

A stem and leaf plot displays numerical data by splitting each data point into a "leaf" (usually the last digit) and a "stem" (the leading digit or digits).
For example, the buyer for a chain of department stores counted the number of pairs of boots at each of the stores and made a stem and leaf plot for the data. Here is the dataset and the stem and leaf plot:
Dataset: $17$, $18$, $20$, $25$, $28$, $34$, $34$, $37$, $38$, $50$
Stem and leaf plot:

Key: represents a store that had $18$ pairs of boots.

## Creating a stem and leaf plot

Here's how to make a stem and leaf plot step by step. We'll use the same dataset as before. Here it is again:
$17$, $18$, $20$, $25$, $28$, $34$, $34$, $37$, $38$, $50$
Step 1: Split each data point into a stem and a leaf. The stem is everything before the final digit, and the leaf is the final digit. Write the stems in a vertical column and don't skip stems just because they don't have any data.
$1|7$, $1|8$, $2|0$, $2|5$, $2|8$, $3|4$, $3|4$, $3|7$, $3|8$, $5|0$
Our $\text{stems}$ are the tens digits:

Step 2: Write each leaf next to its corresponding stem. The $\text{leaves}$ should go from smallest to largest. Our leaves are the ones digits.
$1|7$, $1|8$, $2|0$, $2|5$, $2|8$, $3|4$, $3|4$, $3|7$, $3|8$, $5|0$

Step 3: Give a key that explains what a stem and leaf represent.

Key: represents a store that had $18$ pairs of boots.

## Example: Reading stem and leaf plots

A zookeeper published the following stem-and-leaf plot showing the number of bears at each major zoo in the country:

Key: represents a zoo that has $18$ bears.
Problem A
How many of the zoos have exactly $26$ bears?
zoos

Want to practice more problems like this? Check out this exercise on reading stem and leaf plots.

## Want to join the conversation?

• It looks confusing at first, but is actually very simple.
• If one of the observations was 0, how would this be recorded? Would it be:
0 ¦ 0
?
• Yes, precisely so.
It would be interpreted as 0 tens + 0 ones, which equals 0.
• It's easier than I thought
• Can you do stem and leaf plots with decimals and negative numbers?
• Yes, you can actually. You make the Stem negative If you want the number negative such as -2 | 3 = -23. Now with Decimals, the only way I know how to do it is to edit the key, for example, 2 | 4 = 2.4 that line could instead mean where to place the decimal point instead of separating the 10s place value. Or 1.2 | 3 = 1.23 which is dividing the whole number and the 10ths place value from the hundredths place value from the ones. (I know this question was asked some time ago but hopefully this still helps anyone with the same question.)
• When should I use this kind of representation?
What is the pros?
• This is good for very variant things, I'd say. If you have data that is jumping all over the place in the Tens place, I would definitely use a Stem and Leaf plot.
• Seems to have a confusing process at first glance but once it's started it makes sense.