Scientific working - Correlations

What is a correlation?

Where there is a relationship between two co-variables

What are co-variables?

The variables investigated within a correlation, for example height and weight. They are not referred to as the independent and dependent variables

What can a correlation not tell us?

Cause and effect

Types of correlation

What do numbers tell us in correlations?

-1 - 0 - 1

This is the line of correlations with any - number being a - correlation, + number being a + correlation and 0 being no correlation

What is a perfect correlation?

+1 or -1

What is a weak correlation?

Any number which is closer to 0

What is a strong correlation?

Closer to -1 or 1

When writing hypotheses for correlations, what words should we not include?

Difference, cause, effect e.g. there will be a difference between a and b

When writing hypotheses for correlations, what words should we include?

Relationship, correlation e.g. there will be a relationship between a and b

How do we write one and two tailed hypotheses for correlations?

- 2 tailed - there will be a correlation between a and b

- 1 tailed - there will be a - correlation between a and b

Strengths of correlations.

- As they look at relationships between 2 variables they provide a base level for further studies

- Test whether it is worth doing experiment

- They are easier as less controlled

- Can be tested for reliability

Weaknesses of correlations.

- Lack validity as 2 variables must be fully operationalised

- Not all variables are controlled

- Cannot ascertain cause and effect

What statistical test tests for correlations?

Spearman's Rho