Tehran University of Medical Sciences Journal of Biostatistics and Epidemiology 2383-4196 7 2 2021 07 04 185 192 Soraya Moradi Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Elham Maraghi Department of Biostatistics and Epidemiology, Faculty of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Azar Babaahmadi Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Shima Younespour Dentistry research Institute, Tehran University of Medical Sciences, Tehran, Iran. 2021 05 20 2021 06 08 Introduction: Anxiety in students is a challenge of educational systems. The present study was conducted to investigate the efficiency of Pop Quiz (unannounced formative tests) in teaching biostatistics to postgraduate midwifery students and its effects on their statistics anxiety, test anxiety and statistical analysis skills.  Methods: This quasi-experimental study conducted during the first semester of the academic year of 2019-2020 in the Faculty of Nursing and Midwifery, Ahvaz Jundishapur University of Medical Sciences. The MSc midwifery students were divided into two separate classes. One of the classes was randomly selected for educational intervention (Pop Quiz). Teaching via the lecture method considered as control method. Test anxiety and statistical anxiety questionnaires were completed by the students in both groups before the educational intervention, during and at the end of semester. The final exam score considered as the statistical skills score.Data were analyzed in SPSS 22 using Fisher's exact test and GEE model.  Results: Thirty eight MSC midwifery students (12 in intervention group and 26 in comparison group)were recruited in this study. The mean and standard deviation of the exam score of students in lecture and Pop Quiz groups were respectively 14.43 ± 3.80 and 15.95 ± 2.79 (P=0.182). The patterns of change in test anxiety score differed significantly over time between the two teaching methods (P = 0.003). Although, there was a decreasing trend in mean score of statistics anxiety scores in Pop Quiz group in comparison with lecture based group, but there were not statistically significant differences.  Conclusion: Applying Pop Quiz to teaching biostatistics reduces test anxiety and statistics anxiety and increases statistical analysis skills in postgraduate midwifery students https://jbe.tums.ac.ir/index.php/jbe/article/view/531