Forecast

They are many sources of information to assist with your sales forecast,some key sources are
El major link para forecasts http://www.slideshare.net/siddharth4mba/sales-forecasting

Salesforecasts are common and essential tools used for business planning, marketing, and general management decision making. A sales forecast is a projection of the expected customer demand for products orservices at a specific company, for a specific time horizon, and with certain underlying assumptions.
A separate but related projection is the market forecast, which is an attempt to gauge the size of theentire market for a certain class of goods or services from all companies serving that market. Sales and market forecasts are often prepared using different methods and for different purposes, butsales forecasts in particular are often dependent at least somewhat on market forecasts. Although the focus of this discussion will be on sales forecasting, a brief summary of market forecasting willhelp provide context.
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SALES POTENTIAL AND FORECASTING

Forecasts of different kinds are often prepared at different levels of a corporate enterprise. Managers of different stripes useforecasts for a variety of purposes, including marketing planning, resource\investment allocation, production scheduling, and labor recruitment. In some cases the uses are simply informational, but in manycases forecasts are the basis for major decisions like:
• what product lines to pursue
• how much to spend on production and in what ways
• how aggressively to advertise or promote theproducts
• how best to get the products to market in order to fulfill the projected demand
A sales forecast may cause management to adjust some of its assumptions or decisions about productionand marketing if the forecast indicates that (1) the current production capacity is grossly inadequate or excessive and (2) sales and marketing efforts are inconsistent with the expected outcomes....