An econometric model is one of the tools that economists use to forecast future developments in the economy. In the simplest terms, econometricians measure past relationships between variables such as consumer spending and gross national product, and then try to forecast how changes in some variables will affect the future course of others.

In our world of pharmaceutical drugs, the econometric modelling can determine the relationship between measurable things - like advertising and launch order - and sales. The relationship is usually estimated using regression analysis. The key benefit of econometric analysis is that it focuses on past patterns (sales) response to your actual activities (promotion, launch order etc.) rather than on what customers say (surveys are notoriously unreliable for forecasting).

The key drawback for econometric modelling is that it assumes the past is a good predictor of the future and that one needs to have some back data. It also depends on regression analysis than can uncover "relationships" that are not real. Spurious relationships may appear by coincidence patterns in the background noise.