Correlation coefficient r

The Pearson product-moment correlation coefficient is a measure of strength and direction of association between variables measured in an interval scale or ratio level.

It attempts to draw a line of best fit between these variables, and the Pearson correlation coefficient shows how far these points are away from the line of best fit i.e. the degree to which the relationship is linear.

If your variables are, dichotomous you can use a point-biserial correlation and if you have more than one control variables, you use Pearson’s Partial correlation.

Procedure

1. Click Analyze- Correlation- choose Bivariate
2. Transfer the variables into the variables box.
3. Make sure the Pearson checkbox is selected
4. Click the option button to move to bivariate correlation dialogue box, if you wish to generate some Descriptives, you select on the relevant ones in the statistics area.
5. Click the continue button
6. Click ok to generate the output.

A single output correlation table is generated containing the correlation coefficient, its significant value and the sample size that the calculations were based on.

A bigger value indicates a strong, positive correlation.