How do you think they mark medical students' final exam papers? The extended matching questions are marked by computer. The students use an HB pencil to give their answer and a computer dishes out the marks accordingly. Do you think the computer might get it wrong? Do you think they might have had a problem with the computer in Cardiff? Do you think it could be that they have had recurrent problems with the computer in Cardiff? No, that cannot be the case because if they had had problems before they would be sure to mark them manually. There is no way a faulty computer could have been the cause of the Cardiff catastrophe. Or could it?