Comparison of the Statistics and Item Analysis of Multiple-Choice Questions of Medical and Dental Students' Tests Between Free Admission and Tuition-Paying Admission.

Background: The type of student admission may affect their educational performance. The purpose of this pilot was to compare the multiple-choice test statistics of medical and dental students' tests between free admission and tuition-paying admission under maximum matched conditions. Methods: This descriptive-analytical study was conducted at Golestan University of Medical Sciences in Iran in 2020. The study population included students of medicine and dentistry. A total of 56 tests were selected in two student groups of free admission and tuition-paying admission in basic sciences stages in the physiology course. The matched factors included test features consist of the number of questions, date of the test, test time, the volume of content, topics, and resources, and the instructors. The results of quantitative evaluation of tests were used as the data of this study. There were 21 items for each test including diculty index, discrimination index, the degree of diculty, score variance, and Kuder-Richardson correlation coecient. Results: There were 16 medical and 14 dentistry tests with 437 and 330 questions respectively. The number of medical students participating in the free-tuition and paying-tuition admissions was 1336 and 1076, and for dental students, these numbers were 395 and 235 respectively. There were no signicant differences in normalized adjusted test scores between two admission groups in both medical and dentistry tests. The discrimination index of tests was fair or good, and there were no cases of the negative or poor index. The mean of discrimination index in the free-tuition group was higher than in the paying-tuition group (p = 0.048). The interaction between the type of admission and the eld was signicant for the discrimination index (p = 0.0001). This difference was more in tuition-free dental students than tuition-free medical students and tuition-paying dental students. The mean diculty index and the Kuder-Richardson correlation coecient had no differences in the two groups. Conclusions: The type of student admission has no signicant effect on students’ assessments in multiple choice tests in matched educational conditions. This study was conducted to compare the item analysis of multiple-choice questions among medical and dental students in two groups of tuition-free and tuition-paying students in a maximum matched condition. The results of the present study generally showed that the item analysis of multiple-choice questions among the free-tuition and paying-tuition students was the same. Also, the results showed that the item analysis of multiple-choice questions was the same among students in medicine and dentistry.


Background
Educational researches have indicated the impact of student admission policies on educational performance, both academic and non-academic (1)(2)(3). In terms of paying tuition, student admission policies apply in medical schools for various reasons. Some of these reasons include providing services in rural regions (3), the number of student admittances (4), the provision of primary care physicians, and educational justice (5). The impact of tuition on educational performance is one of the main concerns of educational policymakers in most universities.
In Iran, universities are divided into two major groups in terms of eld of activity. The rst groups are universities that work in the eld of medicine and related elds and are known as medical universities. These universities are managed according to the rules and regulations of the Ministry of Health and Medical Education. The second group is universities in the elds of engineering, art, literature, and other non-medical elds. These universities are managed according to the rules and regulations of the Ministry of Science, Research and Technology. In Iran, universities can be divided into two major groups, government and non-government, in terms of ownership and funding. Accordingly, student admission also includes free tuition and paying tuition. Free tuition is only at public universities and admission with tuition is at public and non-public universities. Admission without paying tuition and using free education has many applicants, and the competition between the candidates is erce and requires a high score in the entrance exam. If the applicant is not accepted in the free tuition government admission, the next option is to apply for admission by paying tuition.
In the case of medicine, the limited capacity of universities and a large number of applicants for medical students cause intense competition even in admission with paying tuition. Of course, the average score level in the entrance exam of those admitted without tuition is always higher than those admitted with tuition. This fact in some cases has led to bias and misjudgment about the ability and educational performance of paying-tuition students.
Various studies have been conducted about the educational performance of paying-tuition and free-tuition students. Some studies state that admission without tuition does not affect educational performance (6, 7) and others point to the effect of tuition on low academic performance (8,9). In most of these studies, the comparison criteria in the two groups of students were not fully matched or could not be implemented. Comparing the grade point average, test scores of different courses, test scores of a simple course in different semesters, and other similar methods without su cient matching of the two groups can be accompanied by bias and error. The present study was conducted in terms of a maximum matching in 56 tests in terms of the course title, instructor, sources of the test, educational content, the volume of course content, time of the test, number of test questions, and holding the test timing at the same time in two independent groups of paying-tuition and free-tuition students. The purpose of this study was to compare the item analysis of multiple-choice questions between paying-tuition and free-tuition medical and dental students in the basic science stage.

Methods
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. A total of 56 tests were selected in two groups of free-tuition and paying-tuition students in basic sciences stages in the physiology course. After matching the conditions including the matching of the test features (number of questions, date of test, test time, volume of content, topics, and resources) and the instructors matching, the results of quantitative evaluation of tests were used as the data of this study. Matching was not considered in terms of the location of the correct option, the number of students participating in each test, 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 tests, 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 test and their quantitative evaluation report. The data were collected based on the o cial test evaluation results of the Education Development O ce and the o cial reports of the education o ce of the medical and dental school and the International Campus, which are the test evaluators and test organizers of medical and dental students for both free-tuition and payingtuition, respectively. The items in these reports for each test included 21 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, di culty index, discrimination index, number of the item with the degree of di culty, number of the item with the ability to discriminate, mean, number of 1, 2, 3, 4, 5, 6 choice questions, Score variance, standard deviation, highest scores, lowest scores, Kuder-Richardson correlation coe cient, and standard error of measurement. The number of questions in different tests was not equal. Therefore, we used adjusted test scores for comparison between two admission groups in both medical and dentistry tests. The 20 was considered as the maximum test score and all adjustments were normalized to it. In this study, we classi ed the di culty index and discrimination index of the tests for different ranges of di culty level and the discrimination index, as shown in Table 1.

Results
In this study, the item analysis of multiple-choice questions for students of medicine and dentistry between free-tuition and paying-tuition courses was compared. The number of tests in free tuition and paying tuition courses in the students of medicine was 16 tests and in the dental students, there were 12 tests. The number of test questions in the free-tuition and paying-tuition courses of the medical students was 437 tests and in the dental students was 330 tests. The number of medical students participating in the free-tuition and paying-tuition courses was 1336 and 1076 students, respectively, and the number of dental students was 395 and 235 students, respectively. The normalized adjusted test scores between two admission groups in both medical and dentistry tests were shown in Fig. 1.
The number of questions based on the di culty index and discrimination index and their relation to di culty and discrimination level is shown in Table 2. According to the ndings, the number of questions with simple and hard di culty in the free-tuition group was more than the paying-tuition group. Also, the number of questions with poor and good discrimination index in the free-tuition group was more than the paying-tuition group.  Table 3 shows the frequency of di culty index and discrimination index of the tests according to the categories by freetuition and paying-tuition groups. No tests were in the moderate and extremely hard level and were often in the hard class. The ndings show that the discrimination index of the tests was fair and good. There were no negative or poor tests for differentiating ability.  Table 4 shows the results of the independent t-test to compare the di culty index, discrimination index, Kuder-Richardson correlation coe cient, and standard error of measurement between two groups of free-tuition and paying-tuition students. According to the ndings, the mean discrimination index of tests in free-tuition students was higher than paying-tuition students, and this difference is statistically signi cant (p = 0.048). The mean di culty index, Kuder-Richardson correlation coe cient, and the standard error of measurement of the tests are not different in the two groups of free-tuition and payingtuition students. Table 5 shows the results of the independent t-test to compare the di culty index, discrimination index, Kuder-Richardson correlation coe cient, and standard error of measurement of the tests between two independent medical and dental students' groups. The nding showed that the di culty index had not differed between the two groups of medical and dental students. According to the results of the Levin test (F = 6.738), the signi cance level was lower than 0.05 (p = 0.012), so for the di culty index, the variance of medical and dental groups was not equal. Discrimination index, Kuder-Richardson correlation coe cient, and standard error of measurement of the tests were not different in the two groups of medical and dental students.
Two-way univariate analysis of variance was used to show the interaction between the type of student admission (freetuition and paying-tuition) and the eld (medicine and dentistry) on the two variables (the degree of di culty and discrimination index of the tests). (Table 6)   Table 6 Univariate two-way analysis of variance to examine the interaction between the type of admission and the eld in the di culty index and discrimination index of tests The interaction between the type of admission and the eld was not signi cant on the di culty index of the tests (p = 0.906) but was signi cant on the discrimination index of the tests (p = 0.0001). Therefore, the mean discrimination index of tests in four groups including the tuition-free medical, tuition-free dental, tuition-paying medical and tuition-paying dental groups was not the same. This was shown in Fig. 1. The type of admission in the medical and dental groups was different so that the mean of the discrimination index of tests in tuition-free dental students was more than in tuition-paying students in that eld.

Discussion
This study was conducted to compare the item analysis of multiple-choice questions among medical and dental students in two groups of tuition-free and tuition-paying students in a maximum matched condition. The results of the present study generally showed that the item analysis of multiple-choice questions among the free-tuition and paying-tuition students was the same. Also, the results showed that the item analysis of multiple-choice questions was the same among students in medicine and dentistry.
The results showed that only the differentiation index of tests between free-tuition and paying tuition students was signi cant. As Taib and Yusoff (2014) pointed, multiple-choice questions can distinguish between good and poor students (10). According to the results of this study, the mean differentiation index of tests in free-tuition students was higher than paying-tuition students, which means that multiple-choice questions in free-tuition students were more differentiated between good and poor students than paying-tuition students. Although the number of test questions was the same for the free and paying tuition students, the variable of student numbers may be affected. The number of free-tuition and paying tuition students was 1731 and 1311, respectively.
In this study, nearly 50% of the questions were considered hard in terms of di culty. This case indicates that the tests were designed appropriately in the sense of di culty. Given that the quantitative evaluation of the questions was done under the same conditions, the quality of questions has no relation with the admission type. Nematbakhsh (2015) points out that students' admission type for free or tuition-paying is not an important issue, but how the student graduates are necessary (11). Therefore, we conclude that the students' evaluation methods, whether free or with tuition, should be such that it leads to the promotion of education quality.
According to the results, the mean, standard deviation, standard error of measurement, and Kuder-Richardson correlation coe cient of the tests showed no statistical signi cance in the two groups of free and paying tuition students in medicine and dentistry. It seems that the type of student admission and their eld do not affect the test results.
The statistical results to examine the interaction between the type of admission and the eld in the di culty index showed that the mean di culty index was the same in both admission type and eld groups. Despite examining the interaction between the differentiation indexes of tests with these variables, the results showed that the mean differentiation index was different between the groups of admission type and eld. Thus, this difference was higher in tuition-free dental students than tuition-free medical students and tuition-paying dental students.
Two limitations need to be considered for interpretation and future research. First, in this study, the educational objectives in different disciplines were not examined. Although the type of content of the educational program is considered in both medical and dental groups, it is suggested that in another study, other variables such as educational goals in different elds be examined. Second, this study was conducted in one course, which limited the generalizability of the results. Thus, this limitation might be considered during the interpretation of the result.

Conclusion
The type of student admission has no signi cant effect on students' assessments in multiple choice tests in matched educational conditions.  The mean and 95% con dence intervals (CI) of normalized adjusted test scores from 20 (Score20) by admission type and student's faculty.