IM Alg1.3.7 Lesson: The Correlation Coefficient

Author:GeoGebra Classroom Activities, IM Algebra 1, Geometry, Algebra 2

Which one doesn’t belong?

A	B

C	D

Sort the cards into 2 categories of your choosing.

Explain the meaning of your categories.

Then, sort the cards into 2 categories in a different way.

Explain the meaning of your new categories.

Take turns with your partner to match a scatter plot with a correlation coefficient.

For each match you find, explain to your partner how you know it’s a match. For each match your partner finds, listen carefully to their explanation. If you disagree, discuss your thinking and work to reach an agreement.

Jada wants to know if the speed that people walk is correlated with their texting speed.

To investigate this, she measured the distance, in feet, that 5 of her friends walked in 30 seconds and the number of characters they texted during that time. Each of the 5 friends took 4 walks for a total of 20 walks. Here are the results of the first 20 walks.

Over the next few days, the same 5 friends practiced walking and texting to see if they could walk faster and text more characters. They did not record any more data while practicing. After practicing, each of the 5 friends took another 4 walks. Here are the results of the final 20 walks. What do you notice about the 2 scatter plots?

Jada noticed that her friends walked further and texted faster during the last 20 walks than they did during the first 20 walks. Since both were faster, she predicts that the correlation coefficient of the line of best fit for the last 20 walks will be closer to -1 then the correlation coefficient of the line of best fit for the first 20 walks. Do you agree with Jada? Explain your reasoning.

Use technology to find an equation of the line of best fit and the correlation coefficient for each data set.

Was your answer to the previous question correct?

Why do you think the correlation coefficients for the 2 data sets are so different? Explain your reasoning.