Objective: Students will see the correlation coefficient and how it changes with the slope of a line. Students will read a graph and communicate what is displayed.
Prerequisite: Students should have calculated the correlation coefficient using a calculator or other statistical software.
NCTM Standards: The student will be able to describe the shape of a scatter plot and its correlation coefficient.
Time: 20 minutes
Answers may vary.
1. The correlation coefficient is the value of r.
2. As the r values get closer to 1 or -1 the slope of the line increases
toward 1 and decreases toward -1
3. When r = 0 the shape of the points is close to a cloud and the equation
of the red line is y = 0
4. When r = 1 the points all fall on the red line and the equation of
the line is y = 1
5. When r is less than zero the slope of the line is negative
6. The r values of -.9 and +.9 produce the shape of a cigar.