Correlation Flashcards
What is correlation?
Quantification of the degree of a relationship in deviations from the mean
What is Pearson’s correlation coefficient?
(r) strength of how X and Y are related
Range of Pearson’s Correlations Coefficient (r) is
[ -1
-1 : Perfect negative Correlation
0 : no correlation between variables
+1 : No correlation between variables
What would most likely the Range of (r) would be?
Decimal
What is the equation for solving (r)?
(r) =____ (x- xmean)(y-ymean) +….. etc.____
sqrt [(x-xmean)^2 +(x-xmean)^2] [(y-ymean)^2+(y-ymean)^2]
Basically what is a Correlation Coefficient?
Strength of a relationship
What matters when solving the Correlation Coefficient (r)?
N = Number of x variables
If you know “N” and “r” , what can it help solve?
P-value
Does a horizontal line and vertical line of correlation?
No
Correlation is NOT Causation. What does this mean?
Just because a variables is related to another, it DOES NOT mean changes in one variable will cause changes in the other
What happens to (r), if N is small?
(r) happens by chance
How do you find Degrees of Freedom when provided only N pairs?
Df= N pairs - 2
How do you find p-value in an r table?
Find the Degrees of Freedom THEN Use provided (r) in the (r) table to see where the (r) would lie THEN this will provide a p-value
How do you find the p-value in a (r) table?
When your (r) value is less than a certain p-value. You would state P
What happens to (r) as (N) gets bigger?
(r) gets smaller
