correlation

Question 1

What are the common names for the x and y variables?

Answer 1

• x variable
  
  • predictor
  • explanatory
  • independent variable
• y variable
  
  • outcome
  • response
  • dependent

Question 2

How do you quantify a relationship between an x and y variable?

Answer 2

• Correlation coefficient (r)
• Aka Pearson’s r
• r = (cov(x,y) / S_x * S_y )

Question 3

r²

Answer 3

• % of the variation in Y explained by the variation in x
• r = 1 is a perfectly correlated line in a positive direction (up and to the right)
• r = -1 is a perfectly correlated line in a negative direction (down and to the right)

Question 4

What does the regression line help with?

Answer 4

1. Describe the data
2. make predictions

Question 5

What is the residual?

Answer 5

• The difference between the observed and expected values