„Econometrics may be defined as the quantitative analysis of actual economic phenomena based on the concurrent development of theory and observation, related by appropriate methods of inference.“
— Tjalling Koopmans
Paul Samuelson, Tjalling Koopmans, and Richard Stone. "Report of the evaluative committee for Econometrica." Econometrica- journal of the Econometric Society. (1954): 141-146.