Lesson 8: Linear Regression

September 24, 2018

Review:

• Scatterplots
• Sum of Squares
• China Travel informational meeting
  • Thu, Sep 27
  • 3:30p-5:30p
  • HSB 108
  • Come and go as you please
  • Scholarships and fundraising assistance available

Presentation:

• Linear regression (simple, bivariate)
  • Calculate equation of the regression line
    • y-hat = b1*x + bo
      • b1 = “slope” of the line
      • b0 = “y-intercept”
    • Calculate Sum of Squares: SSxx, SSyy, SSxy
    • b1 = SSxy/SSxx
    • b0 = (∑y/n) – b1*(∑x/n)
  • Example
    • Beer party data: {(60,10), (70,12), (80,20), (90,40)}
    • Calculate slope (b1) and y-intercept (b0) for linear equation
    • Estimate Beer consumption when temperature is 75 degrees
      • Solve for y-hat when x = 75, x = 85, x = 100 (be careful!)
  • Video

Activity:

• Estimate 2018 voter turnout in Pueblo County using the data below
  • Create a Scatterplot
  • Calculate Sum of Squares: SSxx, SSyy, SSxy
  • Calculate slope and intercept for the regression line and write the linear equation
  • Use the regression equation to estimate turnout in 2018
    • Solve for y-hat when x = 5

Midterm Election	Time Period	Ballots Cast
2002	1	49,304
2006	2	52,957
2010	3	54,471
2014	4	60,543

Assignment:

• Estimate voter turnout for the State of Colorado and bring to class on Wed
  • Gather data from the Colorado Secretary of State Election Results website
  • Use linear regression to estimate turnout, like we did in the activity

• Read pp. 101-105, Correlation and pp. 108-115, Least Squares Regression