在方差分析中，因素就是自变量。因此，只有一个自变量的研究被称为单因素设计。具有多个自变量的研究被称为因素设计（factor design）。构成因素的个别处理条件被称为因素的水平。

The factors in ANOVA are just the independent variables. So the research containing only one independent variables is called single-factor design. The research containing multiple factors is called factor design. The treatment conditions that form the factors are called the levels of the factors.