操作主义于1920年代产生于美国，由美国实验物理学家布里奇曼创建，是主张以操作定义科学概念的一种学说，该学说认为：科学概念与相应的操作同义，凡是不能与操作相联系，不能由操作定义的概念，都是没意义的。

In research design, especially in psychology, social sciences, life sciences, and physics, operationalization is a process of defining the measurement of a phenomenon that is not directly measurable, though its existence is indicated by other phenomena. It is the process of defining a fuzzy concept so as to make the theoretical concept clearly distinguishable or measurable, and to understand it in terms of empirical observations. In a wider sense, it refers to the process of specifying the extension of a concept—describing what is and is not a part of that concept. For example, in medicine, the phenomenon of health might be operationalized by one or more indicators like body mass index or tobacco smoking. Thus, some phenomena are difficult to observe directly (i.e. they are latent), but their existence can be inferred by means of their observable effects. Sometimes, when multiple alternative or even competing, operationalization for the same phenomenon are available, one can repeat the analysis with all of the operationalizations one after the other, to see if the results are impacted by different operationalizations. This is often called conducting a robustness check. If the results are (substantially) unchanged, the results are said to be robust against certain alternative operationalizations of the checked variables.