Correlation Flashcards
Who developed the Pearsons product-moment correlation coefficient?
Karl Pearson - 1895
Correlation (r)
What does a correlation coefficient measure?
Measures the extent to which 2 variables are related
What does the correlation coefficient tell us?
The magnitude and direction of relationship
What type of relationship is correlation coefficient used for?
Appropriate for linear relationships
Why are correlations useful?
Allows us to predict values for 1 variable based on a known value of the other
Line of best fit in a positive correlation
pointing upwards to the right!
Line of best fit for a negative correlation
pointing downwards to the right
No correlation
Points on a graph are scattered with no line of best fit
What is a correlation?
the extent to which the directions and size of deviations from the mean in one variable are related to the direction and size of the deviations from the mean in another variable
What is a positive correlation?
Subjects who score above the mean on X score above mean on Y score, and vice versa
What is a negative correlation?
Subjects who score below mean on X above mean on Y, vice versa
What is Pearson r value range?
-1.00 to +1.00
How do you know if the relationship of a correlation is strong?
The closer r is to -1.00 or +1.00, the stronger the relationship
What is the relationship if r=0
There is no relationship between the variables
What is the coefficient of determination?
The percentage of variance in 1 variable that is accounted for by variance in the other variable
