What is Correlation ?
- Correlation is the relationship between two variables where changes in one variable changes the other
- Two variables are measured quantitivley in order for any correlation to be established
- Only number data is used
- NO IV and DV- they are covaribles
What is a Positive Correlation?
The variables change in the same direction
What is a Negative Correlation?
The variables change in opposite directions
What is Spearman’s Rho ?
It gives you the coefficient of the correlation
What does a Coefficient of 0 mean ?
It means there is no relationship between the variables
What does a value of +1 mean?
It means a perfect, positive correlation
What does a value of -1 mean?
It means a perfect, negative correlation
Advantages of Correlations..
- May indicate a connection between two issue
- Do not require manipulation of variables- more ethical
- Higher Ecological Validity- these numbers came from real life
- Can be used as a starting point for research
Disadvantages of Correlations…
- Don’t prove a casual relationship
- Don’t reflect a curvilinear relationship
- Don’t show cause of the relationship
- Cannot demonstrate cause and effect
- Subject to problems associated with the method used to collect the date- e.g. observation or self report
What is the Third Variable Problem?
Assuming that one variable causes the other when it could be another third variable (causation )
What are the Correlation Coefficents?
+1 - Perfect Positive
- 0 - Zero
- 1.0- Perfect Negative
What is the Alternative Hypothesis?
There will be a significant (direction) correlation between (variable 1) (measured by something) and (variable 2) (measured by something)
What is the Null Hypothesis?
There will be no significant correlation between (variable 1) (measured by something) and (variable 2) (measured by something)
What is Descriptive Statistics?
Summary of data to illustrate patterns and relationships- can’t infer conclusions
What is Inferential Statistics?
Statistical Tests that allows us to make conclusions in relation to the hypothesis e.g. Mann-Whitney or Spearman’s Rho
What is Nominal Data..
Data in categories
What is Ordinal Data…
Data ranked in order
What is Interval Data-
Precise and measured using units or equal intervals
What is Measure of Dispersion ?
Range (Highest- Lowest)
