The procedures used by journal editors, researchers and scientists to review the work, decisions and writings of their professional colleagues – peer groups. Reviewers of scientific papers are commonly called referees, and papers submitted to medical and scientific journals for publication are customarily reviewed by one or more experts in the subject(s) dealt with in the paper. The aim is to improve the quality of the study by pointing out potential pitfalls or errors to the author(s), or to assist medical-journal editors in deciding which papers to prioritise for publication. Evidence that peer review is effective is mixed. Applications for research grants are also usually subjected to peer review. (See also RESEARCH FRAUD AND MISCONDUCT.)