Psychology -> Measures of relationship: correlation and strength of correlation

Measures of relationship: correlation; strength of correlation

Relational research attempts to show how two variables change together. The correlation method of investigation is used when a researcher wants to establish the relationship between two variables. The degree of relationship between the two variables is termed the correlation coefficient. A correlation coefficient not only indicates how strongly two variables are related but also the direction, whether it be positive or negative, of the relationship.

The correlation coefficient, symbolised by the letter r, extends from -1.00 through 0 to +1.00. A correlation coefficient of -1.00 or +1.00 indicates a perfect correlation. A score between these figures would indicate either a strong correlation or a weak correlation. The closer to zero the figure is, whether it be positive or negative, the weaker the correlation. For example, a correlation of 0.55 indicates a stronger relationship between two variables than a correlation of 0.25 and a correlation of -0.85 indicates an even stronger relationship.