Summary: This module is the complementary teacher's guide for the "Linear Regression and Correlation" chapter of the Collaborative Statistics collection (col10522) by Barbara Illowsky and Susan Dean.
Entire courses are given on linear regression and correlation. This chapter serves as an introduction to the topics.
It helps to review the equation of a line. We use
Have the students plot a line by eye using the following data. The independent variable

9  20  27  31  35  40  60 


147  197  297  447  1177  2177  2497 
Ask them what they got for the slope and for the yintercept. Make comparisons. This exercise should point out how difficult it is to get an accurate line of best fit and how many lines "seem" to fit the data. (This data is taken from the exercises.)
For the data above, use either a calculator or a computer and calculate the least squares or best fit line. Look at the scatter plot first. Ask the students if their "by eye" line looks like the calculated one. Explain the correlation coefficient and then check if the correlation coefficient is significant by comparing it to the correct entry in 95% CRITICAL VALUES OF THE SAMPLE CORRELATION COEFFICIENT Table at the end of the reading.
If you use the TI83/84 series, enter the data into two lists first. Then plot the data points on the calculator. First set up the stat plot (2nd STAT PLOT). Then press ZOOM 9 to see the plot. To do the linear regression, go to the LinReg
Line of best fit:
Explain "predicting" (or forecasting) and have them predict the sales price of a 45 inch screen color TV. Have them predict the cost for a mini 5 inch color TV. (The answer is negative.) Discuss that the line is only valid from the lowest to the highest
Have the students follow the "outlier" example in the text and (just once!) do the calculations for finding an outlier. Have them fill in the table below.





Find:
Find
Multiply
Compare each
If any
Have the students do the Practice collaboratively in class.
Assign Homework. Suggested homework: 1, 3, 5, 9, 13, 15 (a  f only if you use the calculator), 21  25.