Abstract: Objective This paper explores the reasons for the bias in student evaluation of teaching (SET) during medical education. Methods This paper uses qualitative research methods. A total of 22 medical students participated in the semi-structured interviews on their evaluation behaviors. Following the coding framework of grounded theory, the interview data were coded using NVivo 12 software. The reasons for bias in SET were summarized and categorized. Results The results showed that 16 primary codes were obtained: teacher personality, teacher misconduct, classroom management, teacher engagement, defensive psychology, revenge psychology, stereotyping, leniency bias, peer influence, career orientation, indicator homogeneity, excessive number of teachers to evaluate, insufficient time, lack of confidentiality, mandatory evaluation, and lack of feedback. These codes were further grouped into 7 secondary codes: teacher-student relationship, classroom atmosphere, students' subjective psychology, students' social psychology, evaluation content issues, unreasonable evaluation timing, and evaluation system issues. Finally, three third-level codes were identified: students′ psychology, flaws in evaluation system design, and quality of teacher-student interaction. Conclusions The bias in SET is the result of multiple interacting factors. Among these, leniency psychology was identified as a unique characteristic specific to medical students′ evaluations. It is suggested that medical universities take multiple measures to rectify bias in SET.

Key words: Students,medical, Student evaluations of teaching (SET), Biases, Qualitative study