Forecasting is the process of estimating future events and problems based on an analysis of past and present data in order to help with planning. It plays a pivotal role in organizational success by aiding in development of effective business controls and implementation of coordinated planning projects. There are various types of forecasts including economic, technological, competition, and social forecasts. Common forecasting techniques involve quantitative time series analysis of past sales data to project future trends, derived forecasts that reuse data from other sources, and causal methods that use mathematical models to connect underlying causes to variables. Additional techniques are brainstorming sessions with experts and the Delphi method of gathering independent expert opinions over multiple rounds.