The following steps may help reduce cheating on multiple-choice and midterm examinations.
Draw your students' attention to the sections of the academic offences (Code of Student Conduct and Disciplinary Procedures, Section III, Articles 15-19) and possible consequences for committing them (Articles 55 and 57). There is less cheating in institutions in which students are aware of official policies.
Explain to your students what cheating is. This is important for at least two reasons: It removes ambiguity. It also reinforces that you and the University care about academic integrity.
All multiple-choice exams with more than 29 questions written by more than 24 students per version are subjected to the Exam Security Computer Monitoring Program. Professors are encouraged to include at least 35 questions in multiple-choice exams, because questions for which many students choose the same wrong answer are excluded from the analysis. The program is run as a matter of course on multiple choice examinations submitted to Enrolment Services for grading. Students are officially notified of the use of the program in the University Calendar. However, to deter cheating, students writing a multiple-choice exam should be informed of the program on the exam itself or, at the very least, before the exam starts
In order to prevent cheating, maybe you can change the type of your test for instance using multiple choice with reasons so they will be busy to think about the answer for the reason of their answer then they do not have time to cheating.
Nabila is right. I have gone through several examination questions and noted something very common to most. The questions are lifted from sections of lecture notes and the students only need to smuggle in the lecture notes and copy therefrom. No attempt is made by the lecturer to phrase the questions in a way that prompts students to think or reason. Cognitive learning is fast leaving universities, at least in my country. I think the lectures themselves need some re-orientation.
I believe that the problem of cheating in exams can be reduced to great extent by switching over to open ended format of questions and open book type of exam pattern.