Correlation matrix

A correlation matrix shows the (Pearson’s) correlation coefficients between a number of variables selected from a table.

Usually it only makes sense to use quantitative (numerical) variables in a correlation matrix. Label variables can be used too, if the measurement is done at the interval level. The matrix makes it easy to see whether there is any statistical relationship between the variables.

The correlation coefficient can only be calculated if neither variable involved is missing(*) (List-wise deletion).

The tab page Cronbach’s alpha

Cronbach’s alpha is a measure of the reliability of a test. It measures the “internal” consistency of a test. If the items measure the same thing they should have a high correlation. The standardized alpha is the alpha you obtain to standardize all variables with the standard deviation.