Lecture 9

Question 1

What is correlation?

Answer 1

As the value of X goes up, the value of Y tends to go up (or
down) either a lot, a little, or not at all
* Can be summarized by single number that tells us how much
the two variables are related (correlation coefficent)
* Tells us how strongly correlated the two variables are
associated

Question 2

perfect correlation

Answer 2

exists between two variables when knowing
the value on one variable always allows us to perfectly predict the
value on the other variable

correlation coefficent is 1 or -1

Question 3

Pearson’s r/correlation coefficent

Answer 3

• Pearson’s r is a correlation score that measures
  how closely two continuous variables are related
• Provides information about the strength and
  direction of a linear relationship
• Ranges from -1 to +1
• -1: perfect negative linear relationship
• +1: perfect positive linear relationship

Question 4

spurious reasoning

Answer 4

correlation does not equal causation