Correlational analysis

What is correlational analysis?

Correlational analysis is a mathematical technique where the researcher looks to see whether scores for two co-variables are related.

What are co-variables in correlation studies?

Co-variables are the variables investigated in a correlation. Unlike experiments, correlations do not have an independent or dependent variable.

What is a scattergram and how is it used in correlation research?

A scattergram is a graph used to plot correlations, where each pair of values is plotted against each other to observe if a relationship exists between the variables.

What is a positive correlation?

A positive correlation occurs when a relationship exists between two co-variables such that as one increases, the other also increases.

What is a negative correlation?

A negative correlation occurs when a relationship exists between two co-variables such that as one increases, the other decreases.

What does it mean if there is no correlation?

No correlation exists when there is no relationship between the two variables.

What is the correlation coefficient and what does it indicate?

The correlation coefficient is a number between -1 and +1 that indicates how strong the relationship between two co-variables is.

What are the correlation coefficient values and their meanings?

• +1.0 – perfect positive correlation

• +0.8 – strong positive correlation

• +0.5 – moderate positive correlation

• +0.3 – weak positive correlation

• 0 – no correlation

• -0.3 – weak negative correlation

• -0.5 – moderate negative correlation

• -0.8 – strong negative correlation

• -1.0 – perfect negative correlation

How should hypotheses be written for correlations?

Use the word “relationship” between the two variables:

• Null hypothesis: No significant relationship between the variables.

• One-tailed hypothesis: There will be a significant positive/negative relationship between the variables.

• Two-tailed hypothesis: There will be a significant relationship between the variables.

What are the advantages of correlations as a research method?

Good pilot study to generate hypotheses for experiments.

• Can research variables that would be unethical to manipulate.

• Can understand the relationship between two variables, including positive/negative and weak/strong relationships.

What are the limitations of correlations?

- Correlations do not show causation – they only indicate relationships.

• They inherit the weaknesses of the method used to gather data for the co-variables (e.g., observation, self-report).

• Cannot show or highlight other variables that may be the real cause.

• Often misleading correlations can occur (e.g., “Bacon causes cancer” may be an erroneous conclusion).