1. Correlation
Correlation: a measure of the extent to which two variables change together.
How well does A predict B?
The correlation may be positive, negative, or have no relationship.

2. Correlation
A positive correlation is expressed when both variables move in the same direction.
Variable A goes up when
variable B goes up
Variable A goes down when
variable B goes down

3. Correlation
A negative correlation is expressed when the variables move in the opposite direction.
Variable A goes up and
variable B goes down
Variable A goes down
and Variable B goes up

4. The strength of the correlation is stated as a correlation coefficient
-1.0
-.5
+.5
+1.0
Negative Correlation
Positive Correlation No
Correlation

5. Correlation
Correlations are graphed on a scatter plot.

6. Correlation

7. Correlation

8. Correlation

9. Correlation

10. Correlation

11. Does this represent a positive or negative correlation?

12. Correlation and Causation
Correlation helps predict, but it does not imply cause and effect.
Association does not prove causation.
Correlation indicates the possibility of a cause/effect relationship, but doesn’t prove it.

14. Correlations

15. Genuine correlation studies can help researchers.
Move beyond observation to organizing information to look for patterns and relationships between variables.
But cannot determine cause and effect.

19. Illusory Correlations
Illusory Correlation is the perception of a relationship where none actually exist.
Perceived non-existent correlation
A random coincidence

20. Illusory Correlations
Illusory Correlation about conceiving children after adopting
Conceive
Do not conceive
Adopt
Confirming evidence
Disconfirming evidence
Do not adopt

21. Female Emotionality Illusory Correlations
Were the participants emotional?
Yes No
Were the participants women?

22. Illusory Correlations
Feline high-rise syndrome
132 cats admitted to Animal Medical Center
Falls ranged from 2 to 32 stories
Only 8 died from injuries
High number of auto accidents during rush hour
The checkout line you join is slowest
Elevator headed in wrong direction

23. Illusory Correlations
Psychic predictions
Out of sync relationships
You want to go out, friend/partner wants to stay at home
You tend to see
what you are looking for