Correlations

What is correlation?

A mathematical technique in which a researcher investigates an association between two co-variables.

What is meant by co-variables?

The variables investigated within a correlation.

What are the different types of correlations?

Positive, negative and zero correlation.

What is a positive correlation?

As one co-variable increases, so does the other.

What is a negative correlation?

As one co-variable increases, the other decreases.

What is zero correlation?

When there is no relationship between the variables.

What are co-variables plotted on?

Scattergrams.

How are scattergrams laid out?

One co-variable is on the x-axis and the other is on the y-axis.

What is the difference between correlations and experiments?

In an experiment, the IV is manipulated in order to see the effect on the DV but in correlations, the variables aren’t manipulated so cause and effect cannot be established, only the relationship.

What are intervening variables?

‘Other variables‘ that have an effect on the co-variables.

What are the strengths of correlations?

• A useful preliminary tool for research.

• May suggest idea for future research is variables are strongly related or demonstrate an interesting pattern.

• Quick and economical to carry out.

Why are correlations a useful preliminary tool for research?

By assesing the direction and strength of a relationships, they provide a precise and quantifiable measure of how two variables are measured.

Why are correlations quick and economical to carry out?

There is no need for a controlled environment of the manipulation of variables.

What are the limitations of correlations?

• Show relationships between variables but cannot explain why.

• We do not know which co-variable is causing the other to change - third variable problem.

• Can be easily misinterpreted or misleading.

• Curvilinear relationships.

Why is the misinterpretation of correlations a limitation?

Relationships between variables are often presented as casual facts when in reality, they may not be.

What is the correlation coefficient?

A numerical value between -1 and +1.

What do statistical tests of correlations produce values between?

-1 and +1.

What does the value of the correlation coefficient tell us?

The strength of the correlation as well as its direction.

What does a value close to +1/-1 indicate?

A strong relationship between the co-variables.

What does a value close to zero indicate?

A weaker relationship between the co-variables.

What does the sign inform us of?

Whether the direction is positive or negative.

What does a value of +1 represent?

A perfect positive correlation.

What does a value of -1 represent?

A perfect negative correlation.

What does a value of 0 indicate?

No correlation.

What is a curvilinear relationship?

A Curvilinear Relationship is a type of relationship between two variables where as one variable increases, so does the other variable, but only up to a certain point, after which, as one variable continues to increase, the other decreases.