The appropriate choice of a statistical test depends on your objective. There are usually two different approaches, depending on whether you are looking for a difference or a relationship among variables:
Difference: This approach informs you whether there is a difference between variables or not.
Relationship: This approach, on the other hand, quantifies the relationship between variables. It can be demonstrated by a correlation coefficient or an equation for predicting an outcome or a classification method.
Once your objective is chosen, it is essential to check the assumptions of the parametric test (black). If the assumptions are violated, you may choose its non-parametric equivalent (grey).