3.2A Least Squares Regression (Ladies and gentlemen, start your calculators!)

Homework Comments 4-step process Make a plot!!!!!

Objectives: INTERPRET a regression line CALCULATE the equation of the least-squares regression line

Least Squares Regression (as seen on the formula sheet) Note there is a difference between our TI-84 output, the textbook and what is printed on the AP Stat formula sheet

LSRL Formulas Given stdev and r, you could find slope Given mean and the slope, you can find the intercept

Miles driven and the price of a used Honda CR-V 22000 17998 29000 16450 35000 14998 39000 13998 45000 14599 49000 14988 55000 13599 56000 69000 11998 70000 14450 86000 10998 Miles driven and the price of a used Honda CR-V

Results of the linear regression of miles driven vs. price

Let’s play with the numbers….

Residual = Observed − Expected Residual = Actual − Predicted The difference between the actual value and that predicted by the regression equation Residual = Observed − Expected Residual = Actual − Predicted

List menu (2nd:Stat) How convenient!

Residuals are important because: They show us departures from the pattern (form). In this case, departures from the linear form.

This scatterplot represents the number of AP Statistics exams taken vs This scatterplot represents the number of AP Statistics exams taken vs. the number of cell phones per 100 people

1993 NL Statistics for MLB Team Games Won Runs Scored Atlanta 104 767 Chic Cubs 84 738 Cincinnati 73 722 Colorado 67 758 Florida 64 581 Houston 85 716 LA 81 675 Montreal 94 732 NY Mets 59 672 Philly 97 877 Pittsburg 75 707 San Diego 61 679 San Fran 103 808 St. Louis 87