Correlations Flashcards
What is a correlation?
A relationship between variables
Correlation indicates how two variables move in relation to each other.
Define a positive relationship.
If you score high on one variable, you will tend to score high on the other
As one goes up, so does the other
If you score high on one variable, you will tend to score high on the other.
Define a negative relationship.
If you score high on one variable, you will tend to score low on another
As one goes up, the other goes down
If you score high on one variable, you will tend to score low on another.
What is Pearson’s Product Moment Correlation Coefficient commonly known as?
Pearson ‘r’
It is a statistic used to measure the strength and direction of a linear relationship between two variables.
What does pearsons r tell us?
Tells us the strength of the relationship (“the size of effect”)
The direction of the relationship
We can also say if it is significant or not (we can give a p-value)
What does Pearson ‘r’ range from?
1 to -1
A value of 0 indicates no relationship.
What does a value closer to -1 indicate?
A stronger negative relationship
The closer to 1, the stronger the positive relationship.
What is the significance of a p-value in correlation?
It relates to the null hypothesis and allows us to reject or accept it
If p is less than 0.05, we can reject the null hypothesis that r = 0.
What is the null hypothesis in correlation?
r = 0
This implies that there is no relationship between the variables.
What factors should be assessed in a correlation?
- How strong the relationship is (strong, medium, weak)
- Direction of relationship (positive or negative)
- If the relationship is significant or not
These factors help in interpreting the correlation results.
True or False: Correlation implies causation.
False
Correlation does not imply causation; it merely indicates a relationship.
What can a third variable in a correlation indicate?
It could explain the correlation between two variables
For example, early educational success may be linked to salary due to intelligence.
What is the assumption of linearity in correlation?
Pearson’s Correlation Coefficient measures linear relationships
It does not measure non-linear relationships.
What is the assumption of normality in correlation?
Your variables of interest are normally distributed
If not, non-parametric methods or data transformations should be used.
What is Spearman’s ρ (Rho)?
A non-parametric alternative that ranks each data set and then correlates the ranks
It does not assume normality and works best with large datasets.
