Why do medical faculties have such a problem with multiple choice questions? (¡°Campus Hunger Games¡±, Opinion, 5 March).

A chicken pecking randomly at four possible answers will score 25 per cent on average, one correct answer for three wrong ones. To reduce that to zero, while keeping 100 per cent unchanged, you award one mark for a correct answer and subtract one third for a wrong answer. One correct = +1, three times one third incorrect = -1. Total equals average equals zero.

It is necessary to make the students answer all the questions and to treat absent answers as wrong. Otherwise, the terror of unexplained negative marking will prevent students from making educated guesses, which will mostly be correct. Clever but nervous students get all their answers correct, but do not answer enough questions to pass.

Such marking procedures are justified because the purpose of an exam is to see how much students have learned or failed to learn.

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Multiple choice questions are difficult to compose well. My daughter, a graduate in modern history, demonstrated to me that she could pass science multiple choice questions by choosing the most carefully written and detailed options and ruling out some distractors using her GCSE knowledge. Multiple choice questions are a useful way of giving marks to students who lack sufficient recall or writing ability to answer ¡°What is¡­?¡± questions but can distinguish between right and wrong answers in questions such as ¡°Which of the following is¡­?¡± It is easy to boost marks by putting in weak, even silly, ¡°wrong¡± answers.

Few faculties still have a will for the exam scrutiny that Kevin Fong described.

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Even more effective at raising marks is to remove negative marking altogether, so that students who know 20 per cent of the answers and guess the rest will average 40 per cent ¨C a pass in most university exams. Multiple choice questions are an excellent way of cutting staff workloads and the marking can be done by non-specialists or scanners. Multiple choice questions also assist in the essential grade inflation which troubled Fong, but they do tax the intellect of academics.

Hugh Fletcher
Retired director of education
Biological sciences
Queen¡¯s University Belfast