Econometrics is a discipline concerned with the application of statistics and mathematics to various problems in economics and economic theory. This term literally means "economic measurement". A central task is quantification (measurement) of various qualitative concepts of economic theory - like demand , supply , propensity to spend , etc.
In contrast to many other research areas using statistics, e.g. psychometrics , controlled experiments are usually impossible in econometrics and, hence, data are treated as observations - "as is". This peculiarity determines the spectrum of the statistical methods used in econometrics: regression analysis , time series analysis , cross-sectional analysis , panel analysis . The design of experiments and related approaches are almost of no use.