Correlation Flashcards
What is the correlation in simple terms?
Correlation refers to a relationship (might be causal but might not) between two variables
What is the correlation in scientific terms?
Correlated variables are non-independent (i.e. if you vary one you tend to get a predictable change in the other)
A relationship (might be causal but might not) between two variables is known as…?
Correlation
How do we measure the amount of correlation?
Covariance
The extent to which a change in one variable is associated with predictable changes in a another variable – i.e. the extent to which they vary together
This is known as…?
Covariance
Define covariance
The extent to which a change in one variable is associated with predictable changes in another variable – i.e. the extent to which they vary together
Simply = as variable y increases, to what extent will variable x also increase or decrease
Are 2 variables related?
Is this a research question investigating causal or correlational relationships?
Correlational relationships
There will be a relationship between pie eating and weight such that the more pies eaten the heavier people will be
Is this a hypothesis investigating causal or correlational relationships?
Correlational relationships
True or False?
Causality can be inferred from correlation
False
Causality cannot be inferred from correlation
True or False?
Just because 2 variables are correlated, does not mean we should conclude that they have causal relationships
True
If we can’t assume that one variable causes another, why do they still have a correlational relationship?
Because there is an underlying variable that causes both of the variables to be related to each other
What are the 4 types of correlation?
1) Perfect positive
2) Perfect negative
3) Imperfect positive
4) Imperfect negative
Define perfect positive correlation
As variable x increases, variable y also increases at the same rate
Straight line going up
Define perfect negative correlation
As variable x increases, variable y decreases at the same rate
Straight line going down
Define imperfect positive correlation
As variable x increases, variable y also increases but not at the same rate
Not a straight line going up
Define imperfect negative correlation
As variable x increases, variable y decreases not at the same rate
Not a straight line going down
What type of correlation is this?
As variable x increases, variable y also increases at the same rate
Straight line going up
Perfect positive
What type of correlation is this?
As variable x increases, variable y decreases at the same rate
Straight line going down
Perfect negative
What type of correlation is this?
As variable x increases, variable y also increases but not at the same rate
Not a straight line going up
Imperfect positive
What type of correlation is this?
As variable x increases, variable y decreases not at the same rate
Not a straight line going down
Imperfect negative
What are the 3 ways to measure linear correlation between 2 variables?
1) Pearson’s r statistic
2) Spearman’s rho
3) Relationships between categorical variables with frequency data using Chi-square
Correlation coefficient is measured by….?
Pearson’s r statistic
What does Pearson’s r statistic allow us to do?
Allows us to conduct a formal analysis to test hypotheses regarding the presence of a linear relationship between variables
When two variables are negatively correlated an increase in one variable will tend to be accompanied by a decrease in the other variable.
a. True
b. False
a. True
In a correlational research design, we commonly manipulate an independent variable and then look for the effect of this manipulation on a dependent variable.
a. True
b. False
b. False
When two variables have a strong positive correlation the implication is that increasing one variable typically causes the other variable to increase
a. True
b. False
b. False
