析因试验在医学研究中常用于病原调查、药物联合作用的评价以及实验条件的分析等。一个较简单的2~p析因设计是p个因子各具2个水平,由于这类设计的主效因及交互作用各仅有一个自由度,因此可利用正交系数以简化计算。但一般要限制各次组的观察数为1个或者成比例。当各次组的观察数不全相等且不成比例时,要分析各因子的主效应 Factorial tests commonly used in medical research in pathogen investigation, the evaluation of the joint effects of drugs and the analysis of experimental conditions. A simpler 2-p factorial design has 2 factors for each of the p factors. Since the main effects and interactions of such designs are only one degree of freedom, orthogonal coefficients can be used to simplify the calculation. However, it is generally necessary to limit the number of observations in each subgroup to 1 or in proportion. The main effect of each factor should be analyzed when the number of observations in each group is not equal and not proportional