In our university, the 5 th and 6 th years medical students receive the MCQ type examination twice a year, in Internal Medicine, Surgery, Pediatrics, Obstetrics and Gynecology and Public Health.
The authors determined the validity of each question about public health (total 130 questions, 1984-1988) according to the percentage of correct answers and the phi coefficient. The results were as follows: 1) With most of the questions, the 6 th year students showed a higher percentage of correct answers and phi coefficient, than the 5 th year students. 2) Most of the questions with a low percentage of correct answers showed a low phi coefficient. 3) The authors analyzed the content and answer pattern of questions with both a low percentage of correct answers and a low phi coefficient, and found to typical reasons for these results, that is, students' lack of knowledge and an inappropriate question. Generally speaking, a question with both a low percentage of correct answers and a low phi coefficient is considered an inappropriate question. Our results showed that in some cases the students' lack of knowlege was responsible for both low figures. It is essential for the teaching staff to determine the validity of the MCQ type examination that they make by means of this kind of analysis.