The Correlational Method Review AP Psychology Ch. 1 Thinking Critically

Defining a Correlation Two variables which vary together in some orderly fashion Relationship can be described as: –Positive –Negative –Zero

Positive Correlation When two variables are positively correlated, you will see one variable increase as the other increases. Positive does not mean good! See Scatter Diagram (page B-8)

Negative Correlation When there is a negative correlation, as one variable increases, the other will decrease Negative does not mean bad! Example of negative scatter plot on B-8

Zero Correlation No relationship exists between the two measures or variables See graph in B-8

Coefficient of Correlation Can be expressed as a number: Close to zero-relationship is weak perfect positive perfect negative

Correlation Vs. Causation Just because a relationship exists between two variables, this does NOT indicate cause and effect Always look for a third variable!

Examples of Correlations Label as positive or negative… Children who view violent TV programs will exhibit more violent behaviors Individuals who exercise will achieve a loss of weight. Workers who are given a coffee break will increase their productivity.

Examples of Correlations Children who receive the flu vaccine are less likely to suffer from the flu. Children who listen to rock or rap music are more likely to get into trouble. Patients given Advil find relieve from migraine headaches.