Example 1

An education research team is interested in determining if there is a relationship between a student’s vocabulary and how frequently the student reads books. The team gives 20 students a 100-question vocabulary test, and asks students to record how many books they read in the past year. The results are in the following table. Is there a linear relationship between the number of books read and test scores? Use the correlation coefficient, r, to explain your answer.

1. Create a scatter plot of the data.
2. Describe the relationship between the data using the graphical representation.
3. Calculate the correlation coefficient on your graphing calculator.
4. Use the correlation coefficient to describe the strength of the relationship between the data.

This applet is provided by Walch Education as supplemental material for their mathematics programs. Visit www.walch.com for more information on their resources.