L6: correlation & simple regression

Question 1

sample co-efficient r

Answer 1

-1 ≤ r ≤ 1

Question 2

positive correlation and r

Answer 2

r > 0

Question 3

negative correlation and r

Answer 3

r < 0

Question 4

zero correlation and r

Answer 4

r ≈ 0

Question 5

r closer to +1 line shape

Answer 5

straight w positive slope

Question 6

r closer to -1 shape

Answer 6

straight line w negative slope

Question 7

correlation coefficient variables X and Y

Answer 7

doesn’t matter which is which

Question 8

spurious correlation

Answer 8

variables (e.g. ice-cream sales & crime rates) closely correlated, but not causally linked w each other. (hot temperatures) 3rd variable affects both variables separately. Failing to account for 3rd = research biases

Question 9

simple regression dependent variable

Answer 9

Y

Question 10

simple regression independent variable

Answer 10

X

Question 12

regression measures & explains

Answer 12

effect of X on Y, explanatory variables that influence Y

Question 13

error (ei)

Answer 13

vertical distance between observation Yi and predicted Y hat I -> [Yi - Y hat I]