Topic 5 Flashcards
What variables are talked about in correlation?
Dependent only
If variables are related they are said to be…
Correlated
Does correlation include Independent variables? What is the consequence of this?
No, therefore it can only be used to describe and predict but NOT explain/infer causality
Explain positive correlation and how the graph represents this
As one variable increases, the other increases
The graph plots tilt upwards from Left to Right
Explain negative correlation and how the graph represents this
As one variable increases, the other decreases
The graph plots tilt downwards from Left to Right
Explain zero correlation and how the graph represents this
There is no consistent relation between variables
The plots are scattered with no pattern
Describe a strong correlation
Scores are more closely groups around an imaginary line
What does a stronger correlation give?
Better predictability
What is the numerical way to express correlation?
Pearson R
What values does r range between?
-1 to +1
To correlate variables how must they be measured
Measured on the same individual
What 2 scales must the correlation variable be measured on?
Interval or ratio scale
TRUE or FALSE
r can detect all relationships
FALSE
r can only detect linear relationships
What does it mean when r = 0, or is low?
- May mean no relationship
- The relationship might be non-linear
- Range could be restricted i.e not enough spread/variability
Describe a curvilinear relationship
Increase in x initially increases y, then decreases y
e.g. Yerkes-Dodson arousal curve
