Overview
This lesson explains how to construct a stem-and-leaf plot, a graphical tool for visualizing data distributions and identifying outliers.
Purpose of Stem-and-Leaf Plots
- Stem-and-leaf plots graphically show the distribution and pattern of a data set.
- They help identify outliers (extreme values that differ from others).
Steps to Create a Stem-and-Leaf Plot
Step 1: Set Up the Table
- Create a two-column table with stems on the left and leaves on the right.
- A vertical bar may separate stems from leaves.
Step 2: Determine Stems and Leaves
- The leaf is the rightmost digit of each number.
- The stem is all digits to the left of the leaf.
- For single-digit numbers, the stem is 0.
- Include stems for all ranges (even those with no values, like 50s).
Step 3: Record Stems
- List all stem values in order (e.g., 0, 1, 2, ... 10) in the left column.
Step 4: Add Leaves
- Write each leaf (rightmost digit) to the right of its corresponding stem.
- Include all leaves, repeating any values that occur more than once.
- Line up leaves vertically under each stem for clarity.
Step 5: Add a Key
- Include a key explaining how to interpret the plot (e.g., 5 | 7 means 57).
Key Terms & Definitions
- Stem-and-leaf plot — A table that organizes data into stems (leading digits) and leaves (final digits).
- Outlier (Extreme Value) — A data point that does not fit the general pattern of the data set.
- Stem — All digits of a number except the last one (on the left).
- Leaf — The last digit of a number (on the right).
- Key — A legend clarifying how to read the plot values.
Action Items / Next Steps
- Practice creating a stem-and-leaf plot using a new data set.
- Ensure to write a clear key for every stem-and-leaf plot you construct.