With the increasing role of economic uncertainty, improving the efficiency of forecasts is ever so important. This book makes suggestions on how to evaluate the key economic indicators under uncertainty. It presents the interval method to study economic indicators, which will allow us to understand the possibilities of forecasting and the irregular nature of the economy. It is shown that with the accumulation of negative phenomena in a seemingly stable situation the effect of a compressed spring may snap into action. The book outlines the uncertainty relations in the economy, the minimal uncertainty interval, the effect of an expanding uncertainty band, sensitivity thresholds, as well as the principles of systematization and forecasting of economic indicators. The book presents ways to facilitate economic development, assess the quality of a forecast, and increase the efficiency of forecasts and decision-making in conditions of uncertainty.