Correlational Research

Statistical analyses of relationships between variables.

Purpose

• To identify relationships and assess how well one variable predicts* another.– *Meets psychology goal of prediction.

• It does NOT show cause and effect!

Importance

• Understanding correlations can help us lead safer and more productive lives.– Ex. Correlational studies have repeatedly found

high correlations between birth defects and a pregnant mother’s use of alcohol.

• This kind of information allows us to reliably predict our relative risks and to make informed decisions.

Caution

• A correlation between two variables does not mean that one variable causes another.– Ex. Some media reports about stress and cancer.

There is a correlation but does stress cause cancer? What else might contribute?

Types of correlation

• Positive• (same)

– Both factors move in the same direction

• Negative• (different)

– Both factors move in the opposite direction

Or

Or

Positive Correlation

As studying goes up, grades tend to go up!

Positive Correlation

• As a child’s screaming decreases, so does its mother’s stress level.

Negative Correlation

• As typing practices increase, errors decrease!

Negative Correlation

• As stress decreases, health improves (increases)

Zero Correlation• There is no relationship

Is it true? If you were glasses then you must be smart.

Illusory Correlation

• If I wear my lucky socks then I will win my match.

The perception of a relationship between two variables when only a minor or absolutely no relationship actually exists...

Some potential questions that may be answered with correlational studies

• Are people who are experiencing severe stress more prone to develop physical illness than people who are not?

• Are children whose parent(s) have schizophrenia more likely to develop this disorder than other children?

• When someone needs help, is it more likely that someone would help them if many bystanders are present or just a few?

Quiz: What type of correlation?1. As a professional bowler’s score goes up, the amount of money

he makes goes up.Answer: Positive

2. As a professional golfer’s score goes down, the amount of money he makes goes up.Answer: Negative

3. A researcher finds that students who attend fewer classes get poorer grades.

Answer: Positive 4. The more ice cream sandwiches someone eats, the greater

their ability in math will beAnswer: Zero

5. Nick wore his lucky batting glove and hit two home runsAnswer: Illusory