The research study described in your text tested the ability of graphologists to discriminate among people in different occupations because graphologists claim to have special expertise in the area of predicting:

Question

Quizplus · Accepted Answer

The study specifically tested the ability of graphologists to differentiate based on occupation, which suggests that the prediction being tested is about which job applicant will be successful in a particular occupation.

The Research Study Described in Your Text Tested the Ability