Correlation (co-relation) Refers to: 1. how strongly one variable is related to another. 2. the direction of the relationship.

Positive Correlation When variables increase together or decrease together.

Negative Correlation When variables move in opposite directions. i.e.. one goes up- the other down.

Correlation Coefficient - a coefficient includes an absolute value i.e..02 or.50, and either a + or - sign. - the sign ( + or - ) indicates its direction - a zero indicates NO correlation between variables To describe correlations- psychologists calculate a statistic called a: “correlation coefficient”.

Correlation Coefficients

The absolute value indicates the strength of the relationship. I.e is a stronger correlation than +.45 and +.75 is stronger than -.22 Though correlation may be strong, it does not imply that one variable causes the other.

Correlation does not imply causation!

Correlation in the media Here are some recently reported correlations, with the interpretations drawn by journalists noted in parentheses. In the absence of experimental research, can you come up with other possible explanations for each of these? 1.Attention disorder linked with drug abuse. (Interpretation: Children with ADHD have poor academic performance and peer difficulties which makes them susceptible to abusing drugs.) 2.Toddlers who watch more than two hours of TV per day perform worse in school than those who watch less. (Interpretation: TV viewing makes children bad students.) 3.Educated people live longer, on average, than less-educated people. (Interpretation: Education lengthens life and enhances life.) 4.People who spend long hours on the Internet are somewhat less engaged with family and are lonelier and more depressed. (Interpretation: By isolating people from face-to-face contact, Internet absorption can be depressing.)

Measures of Correlation One of the fastest ways to determine if 2 variables are correlated is to draw a scatter plot. A scatter plot can tell us:  if a correlation exists  how strong it is

Scatter Plots

Which is a stronger correlation? or or or +.04

What is an Illusory Correlation? When we believe there is a relationship between 2 things- we are likely to notice and recall instances that confirm our belief.

Illusory Correlations e.g. Positive thinking people being cured of cancer. ab cd Positive Thinking No Technique Technique Used Cured Not Cured Much Apu About Nothing be.com/watch?v=S dBn5G7Y2RA