The present study was a descriptive-analytical study that was conducted cross-sectional in 2020 at Golestan University of Medical Sciences in Iran. The study population included students of medicine and dentistry. Medical and dental students have nearly identical curriculums and educational programs in their basic science stage. This stage includes the first four semesters. A total of fifty-six physiology course exams were selected in two groups of free-tuition and paying-tuition students in basic sciences stages of medicine or dentistry. After matching the conditions including the matching of the exam features (number of questions, date of exam, exam time, volume of content, topics, and resources) and the instructors matching, the results of quantitative evaluation of exams were used as the data of this study. Matching was not considered in terms of the location and order of the correct answers of multiple-choice questions, the number of students participating in each exam, and other student-related conditions such as admission quota, gender, or grade point average due to limitations and impossibility. It should be noted that at the time of the exams, none of the teachers, learners, facilitators, and colleagues had any information about the presentation of this study, and the idea of this research was developed long after the exams and their quantitative evaluation report.
For increasing the power of the study and provide a proper sample size, we included both medical and dental students’ exams. During the basic science stage, which consists of the first four semesters, the medical and dental students have almost the same educational programs and very similar curriculums. The physiology course of medical and dental students is also very comparable to each other. Therefore, we assumed considering both medical and dental exams’ data had no bias on results.
The data were collected based on the official test evaluation results of the Education Development Office and the official reports of the education office of the medical and dental school and the International Campus, which are the exams evaluators and exams organizers of medical and dental students for both free-tuition and paying-tuition, respectively. The items in these reports for each exams included twenty-one parameters, which are the title, date, correct answer score, incorrect answer score, no answer score, passing score, number of options, number of questions, number of candidates, difficulty index, discrimination index, number of the item with the degree of difficulty, number of the item with the ability to discriminate, mean, Score variance, standard deviation, highest scores, lowest scores, Kuder-Richardson correlation coefficient, and standard error of measurement. The number of questions in different exams was not equal. Therefore, we used adjusted exams scores for comparison between two admission groups in both medical and dentistry exams. The number of questions and the maximum score of the exam were different among these fifty-six exams. Therefore, they must be normalized for statistical analysis. Because the twenty is routinely considered as the maximum exam score in Iran’s educational system, this value was considered as the maximum exam score and all adjustments were normalized to it.
In this study, we classified the difficulty index of each question into five categories: simple, moderate, hard, very hard, and extremely hard. We also classified the discrimination index of each question in for categories: negative, poor, fair, and good.
A Chi-square test was used to compare qualitative variables. The Kolmogorov-Smirnov test was used to test the normality of quantitative data. Tables and graphs were used to describe the variables. Independent t-test and Mann-Whitney test were used to compare quantitative variables between the two independent groups. Two-way univariate analysis of variance was used to investigate the interaction of independent variables on quantitative variables. Statistical package for the social sciences (SPSS) software version 22 was used for statistical analysis. This study was approved by the ethical committee and the institutional review boards of the Golestan University of Medical Sciences (code: IR.GOUMS.REC.1397.159).