The Conservatives have called on the government to review the A-level system after a study indicated that results have been "adjusted downwards" in recent years. Carol Fitz-Gibbon, professor of education at Durham University and adviser to the Qualifications and Curriculum Authority, tested pupils from 900 schools in 1996 and 1999. A comparison of the results showed that candidates of similar ability were scoring one grade better than they would have done three years earlier, particularly in maths and science. Shadow education spokesman Tim Boswell said that the survey cast doubts on the efforts of pupils and teachers.