1. Historical factors, also known as time factors, refer to the major factors that may affect the health-related behaviors of the target population during the implementation or evaluation of health education and health promotion plans, such as the introduction of health-related public policies, major changes in living conditions, natural disasters, etc. Proficiency factors include the maturity of the measurer and the maturity of the measured object. The maturity of surveyors is due to the fact that with the progress of the project, surveyors and other project staff can be more and more proficient in project activities and use measuring tools and technologies, resulting in measurement deviation, which is manifested in the fact that the same content is measured with the same tools, and the test results in the early stage are different from those in the later stage. The maturity of the measurement object is due to the maturity of the target population during the project, which may make the measurement result better than the real result of the project intervention. The lost-visit factor refers to the inability to intervene or evaluate the target population due to various reasons, such as death, relocation, voluntary withdrawal, etc. During the implementation or evaluation of health education and health promotion plan. According to this, "natural disasters in the project area" is a historical factor, "increased work experience of investigators" is a skill factor, and "residents cannot be tracked because of demolition" is a lost visit factor.