Pearson's R Flashcards
Quantitatively expresses the extent to which two variables are related
Measure of the strength and direction of association that exists between two variables measured as scale variables (ratio or interval)
What are the 2 things Pearson’s R tells us?
- The direction of relationship between the X and Y (positive or negative; linearity)
- The strength of the relationship between the X and Y (stron, moderate, or weak)
If r=+1
Denotes perfect positive correlation
If r=-1
Perfect negative correlation
If r=0
No relationship bet. 2 variables
One variable gets larger than the other
r is positive
One variable gets larger, one variable get smaller
r is negative; also called an inverse correlation
0.00 to +- 0.19
Very weak
0.20 to +- 0.39
Weak
0.40 to +- 0.59
Moderate
0.60 to +- 0.79
Strong
0.80 to +- 1.0
Very strong
What are the assumptions needed in order to use the Pearson r?
- The variables must be either interval or ratio measurement
- The data must be approximately normally distributed
- There is linear relationship between the two variables
- outliers are either kept to a minimum or are remove quickly
- There is homoscedasticity of the data
Sample size is less than 50
Shapiro-Wilk Test
Sample size is greater than 50
Kolmogorov-Smirnov Test
