Econometrics: The attempts of statisticians and mathematicians to discover economic laws and solve problems of human action by the use of statistical data which necessarily relate to the past. Econometricians maintain that science is measurement and assume both a constancy and regularity in economic data that permits them to use precise mathematical measurement for testing and developing economic theory.
Actually, the only measurable magnitudes of human action are those related to historical facts. The ideas and value judgments which determine human participation in the market process are neither constant nor certain. All future human actions are thus uncertain variables which are incapable of either quantification or measurement. Consequently, the use of mathematics, as a means for determining economic theory applicable to future human actions, is futile.
- Ludwig von Mises, Mathematical Economics