现场实验是流行病学方法之一。通过疾病分布描述和流行机理分析,对疾病发生或流行的因素(对已知病因的疾病)或病因(对未知病因的疾病)建立了病因“假说”,通过专题调查或实验研究进一 Field experiments are one of the epidemiological methods. Through the description of disease distribution and epidemiological analysis, etiological “hypothesis” is established for the factors causing or prevalent diseases (diseases with known causes) or etiologies (diseases with unknown causes), and then through special investigations or experimental studies