Modules Week 7

Question 1

What is correlation?

Answer 1

Concerned with relationship between two variables (e.g. Age and IQ)

Do we get smarter as we get older?

Question 2

Describe Correlation checklist

Answer 2

Variables = x and y

Each participant gives 2 pieces of data (e.g. age and IQ = 15 and 100)

Simple observation, no control or manipulation
Examines linear and symmetrical association

In + linear association, as scores on x increase, so do scores on y
OR high scores on x are related to high scores on y

In - linear association, as scores on x increase, scores on y decrease
OR high scores on x are related to low scores on y
Observed association is just that: observed and nothing more

Correlation does NOT tell us about direction of effect (causation), so no IV and DV

Is possible another variable explains observed relationship (e.g. education)

Question 3

Describe Pearson’s r

Answer 3

Pearson’s r measures the strength of the linear relationship between x and y

The value of r lies between -1 and +1

The size of r specifies how close the data is to a straight line (how strong the linear association is)

Sign of r specifies direction of association

Question 4

Describe Pearson’s r in JASP

Answer 4

Will tell us strength and direction of correlation

Determines if we can infer that an association observed in a sample (r) is also present in the population (p; rho).

If r is large enough, so that it is extreme in a distribution of sample correlation coefficients then we can infer and association between 2 variables in the population

Like distribution of sample means in different form