Box-Whisker Plots on TI-89

Summary: You can use your TI-89 to create a box-whisker diagram, also known as a boxplot. Boxplots give you a general idea of the shape of the data, particularly its skew, and they highlight outliers in the data set.

Alternatives: If you have a TI-83/84, see Box-Whisker Plots on TI-83/84 or use MATH200A Program part 2.

Let’s make a boxplot of this data set:

Step 1: Enter the numbers in a list.

Get into the Stats/List Editor.	[◆] [APPS], select Stats/List Editor, and you should be on the list entry screen.
Enter the data points.	Cursor to the heading list1 (not the first data line) and press [CLEAR] [ENTER] to clear the list.   Enter the x values. (The order doesn’t matter.)

Step 2: Clear other plots.

Step 3: Set up the boxplot.

Get to the Plot Setup screen, and select a modified boxplot. (“Modified” means it shows outliers if there are any.)	Press [F2] [1]. Then, cursor to an empty plot, or one you don’t care about keeping.   Press [F1] [►] [5].
Fill in the Define Plot screen.	Use the [ALPHA] key to type list1: [ALPHA 4 makes l] [ALPHA 9 makes i] [ALPHA 3 makes s], then plain [T] [1] [ENTER] [ENTER].

Step 4: Display the boxplot.

On the box-whisker diagram, any outliers show as isolated squares. The whiskers are mix and max (disregarding any outliers), and the box is first quartile, median, and third quartile.	Press [F5], which is ZoomData or “zoom to statistics data”.
Identify the outliers, if any.	Press [F3] to trace on the plot. Use [◄] and [►] to display the numbers in the five-number summary as well as any outliers. Here, you see that there is an outlier with a value of 22.