Chapter 5: Regression

Question 1

Linear regression objective

Answer 1

-To quantify the linear relationship between x and y variables

Question 2

Least squares regression line

Answer 2

• Describes how average value of y changes depending on value of x
• Minimizes the sum of the squared vertical distance of the pts from the line

Question 3

Coefficient of Determination (R2)

Answer 3

• Measures predictive accuracy of regression line

- Between 0-1: fraction of variation in y values that can be explained by the regression line

Question 4

Outliers-residuals vs influential

Answer 4

• Outliers in x direction: often influential in regression line
• Outliers in y direction: large residuals
• Regression and correlation are sensitive to outliers

Question 5

Cautions: correlation and regression

Answer 5

• Only linear relationships
• Sensitive to outliers
• Beware of extrapolation
• Lurking variables
• Correlation does not mean causation (reverse causality, lurking variables, etc.)