This InspireData lesson plan explores tobacco use data from the United States to teach about correlation, line of best fit and the correlation coefficient. If students are not ready to learn about line of best fit and the correlation coefficient, this can be an activity simply about identifying correlation between two variables.
• Open the database Tobacco Use inside InspireData: InspireData Starter Screen>Databases>Mathematics>Tobacco Use. Discuss the table and each field. Refer to any field notes for additional information.
• For each plot, have students complete/answer the following. Use the plots in the attached file, or have students create their own plots.
o Does the graph show positive, negative, or no correlation?
o Write a sentence that describes the situation in context (for example, “In general, the higher the percentage of adult smokers in a state, the higher the percentage of high school smokers).
o Add a line of best fit and write one prediction using the line of best fit (for example, “If 35% of adults in a state were smokers, I would predict that 38% of highschoolers were smokers.”). Hint: it may be helpful to change the maximum values on both axes to extrapolate from the data and make predictions.
o What does the correlation coefficient indicate? Mark any outliers. What is the impact of outliers on the correlation coefficient? To explore the impact of outliers, select any data point, right click and select “exclude selected icons.” Note any changes in the correlation coefficient. If there are no outliers, exclude points that are farthest from the line of best fit. (For example, “The correlation coefficient is .60, which indicates a moderate positive correlation. As I exclude data that is farthest from the line of best fit, the correlation coefficient gets closer to 1 because the line of best fit is a stronger indicator of the pattern.)

This activity was created using InspireData 1.5, which must be installed to open the file. Download a 30-day free trial at href="http://www.inspiration.com/freetrial">www.inspiration.com/freetrial or if you have InspireData 1.0, download a complementary upgrade.