You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Effectiveness of an educational intervention on prescription writing skill of preclerkship medical students in a problem-based learning curriculum. Medical school training for students in pharmacotherapy is suboptimal and junior doctors are not confident to prescribe drugs. This study evaluated the effectiveness of an optional educational intervention on prescribing skill of pre-clerkship medical students in a problem-based learning (PBL) program. Performance was assessed in seven end-unit objective structured practical examinations (OSPE). Physician-related prescription components (PRCs) and drug-related prescription components (DRCs) were assessed. The performance of students who attended the intervention sessions (attendees) and non-attendees was compared. Approximately half of the students attended the sessions. PRCs were written appropriately by most of the students. DRCs were written less competently by both attendees and non-attendees, specifically the dosage form, quantity to be dispensed and directions. Performance on individual DRCs was significantly better for attendees compared to non-attendees. The mean total score for all prescription components of attendees was significantly greater than that of non-attendees. The percentage of high achievers was significantly greater for attendees. A positive correlation was found between student attendance and the total score. An optional educational intervention during the preclerkship phase is an important determinant of prescribing performance of medical students.
{"Chemical": []}