In order to plan the budget for a project, many costs are not known in advance. Forecasting is used in order to estimate what these costs will be. Forecasts can never be completely accurate, but can provide a good idea of what to expect if the appropriate techniques are used. Some forecasting techniques are less accurate than others but are used to start off planning. When more detailed data becomes available, more accurate forecasting techniques can be used. What follows is a survey of forecasting techniques and their benefits and limitations. The techniques are divided into four major areas: ad hoc, numerical/statistical, simulation, and earned value analysis.