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Howard Allen implies that if teaching is effective, distributions of grades should be heavily skewed towards firsts and upper seconds (Teaching, É«ºÐÖ±²¥S, February 9). For too long, fetishes have been made of grade distributions that are normal in the statistical sense. Further, it is time assessors appreciated the law of small numbers - that distributions in a small sample are unlikely to resemble those in a large one - and that this could explain why, in a cohort of, say, 120 students, six different tutors might each have marked 20 assignments with divergent distributions of grades. This makes one question whether checking cross-tutor parity in grade distribution really is part of quality assurance?

Anthony Edwards
University College Northampton