The teacher felt that the student lacked discrimination in the study of his data.

Imagination : the faculty or action of forming new ideas, or images or concepts of external objects not present to the senses.
Taste : the sensation of flavour perceived in the mouth and throat on contact with a substance.
Objectivity : the quality of being objective.
Discernment : the ability to judge well.
Discrimination : the ability to judge what is of high quality; good judgement or taste.

Synonym of Discrimination is Discernment