Unit 13b: Regression II Multiple Regression

Question 1

why do we use more predictors

Answer 1

to “control” for additional sources of variation

• Multiple regression uses additional predictors to explain more variation in the outcome variable
• Increases R-squared
• Increases our precision
• Helps us make better predictions
• Reduces bias in a predictor variable
• Helps us estimate a better effect

*not causal unless you design an experimental study

Question 2

Answer 2

A zero inch tall person is predicted to weigh about −260.4
lbs.

Question 3

Answer 3

Question 4

difference between simple and multiple regression

Answer 4

multiple regression has multicollinearity- if two variables have above .9 as a correlation, remove one of the variables because they share too much variance in common and tell you the same thing

Question 5

correlation coefficient is between:

Answer 5

-1 and 1