Mathematics · Hypothesis Testing and Degrees of Freedom

A clinical psychologist is evaluating ordinal data from two independent groups to compare their overall well-being scores. Group 1 consists of 18 patients, and Group 2 consists of 22 patients. Because the data is ordinal and violates normal distribution assumptions, the psychologist correctly utilizes the Mann-Whitney U test, which is a distribution-free statistical tool ideal for such conditions. However, if the psychologist had mistakenly ignored the assumptions and applied the corresponding parametric alternative test to compare these two independent groups, what would be the calculated degrees of freedom (df) for that parametric test?