Correlations

Question 1

What do correlations show?

Answer 1

Quantify relationships
Strength of relationship
How much of the variance in one variable is explained by another

Question 2

What is the correlation coefficient?

Answer 2

Size of the effect 
No relationship: r= 0
Perfect relationship : r=+1, positive relationship
r= -1, negative relationship.
0= no relationship.

Question 3

How to calculate how much variance is explained by the model?

Answer 3

Squaring the correlation coefficient

Convert to percentage

Question 4

What command calculates Pearson’s correlation in R?

Answer 4

cor.test()
Need to know x , y, method.

We can access variable x and y by using the $ symbol
Variable x = df$x
Variable y =df$y

cor.test(x = df$xvariable, y= df$RPE, method = “Pearson”)

Question 5

What does squaring the correlation coefficient show?

Answer 5

How much variance in one variable is explained by another variable