Curriculum settings
The participants were divided into the experimental group and the control group using the method of random number table of the simple randomization. The members of both two groups were required to attend theoretical courses. The study included four theoretical classes in total, lasting for a month and each week, students took a theoretical course. A theoretical course took approximately 4 h. The first theoretical course was the introduction to clinical epidemiology, which introduced the history and development of clinical epidemiology. The second course consisted of an overview of common epidemiological research methods, and students learned about the design, advantages and disadvantages of various epidemiological methods, including cross-sectional studies, case‒control studies, cohort studies, and experimental studies. The third theoretical course focused on practical epidemiological research and included statistical description and analysis, providing students with a clear understanding of data collection, data entry, statistical description and statistical inference. Investigator training was a prerequisite for the epidemiological practice course, and we set it as the last course in the theory series. The course contained how to be an investigator from the beginning of proposing research questions, research design and implementation, data collection, statistic analysis and result discussion, as well as communication skills, data-gathering techniques, which were honestly needed in the actual research process. On the one hand, this allowed students to review the content of the previous lessons through the questionnaires used in practice. On the other hand, it ensured that students could complete the practice course with high quality.The epidemiological practice course conducted in community was only applicable to the experimental group and the community practice course was conducted after each theoretical course in the last two weeks. All the students engaged with every link in a cohort study that was specifically designed for this course. When students in the experimental group conducted the practical course in the community, students in the control group were arranged self-learning in the cohort study cases. The specified cohort study began with a literature review, then a research purpose was proposed and the research contents were determined. The next step involved research design and implementation, which included determining the study method, exposure factors, health outcomes, study site, study population and sample size. Next, students participated in data collection, and in this section, medical ethics and data authenticity were also considered. Students conduct statistical analysis after the completion of data collection. Finally, they discuss the results and possible biases of the study. The practical course conducted in the community was in conjunction with a field test that aimed to develop a more specific health literacy scale for elderly Chinese individuals [