How accurate are sales forecasts?
ONE should understand that the sales forecast is not exact but should be as accurate as one could reasonably expect for the business he/she is in and that, through measurement and correction of errors, the sales forecast accuracy is improving on a product by product basis.
It is mainly the job of planning, purchasing and production departments to be able to meet the sales forecast given this expected level of accuracy. However, it is not necessary to have an accurate forecast to plan and control your business; you do need everyone to work to an agreed forecast that is updated regularly with any significant changes.
Forecast accuracy also will depend on the historical business background you are in. If you are in a mature and stable business you should expect a reasonably accurate forecast. If the business is new and growing, the forecast will be less accurate. In either case the way to determine what your forecast accuracy should be is to start with the accuracy you have achieved in the past. This is the minimum starting point for forecast accuracy. If you do not have a formal forecasting process at the moment, you should start now.
Forecast accuracy should be measured in units of production not value unless there is no sensible unit of production (a company selling a service for instance). An important reason to measure forecast accuracy is to be better able to plan the future supply chain and value adds in factors such as selling price and even exchange rates into the forecast accuracy which do not affect the supply chain. Average selling price and exchange rate should be forecast as a separate exercise for financial planning.
Once you are measuring sales forecast accuracy, the next stage is to improve it. This is achieved by investigating any forecast errors outside the historical accuracy of the forecast.
Finally, the sales plan should be the date and quantity of shipments you expect your customer may require. If your customer requests products in line with the plan, but you are unable to ship that product, it is still a hit as far as plan accuracy is concerned. On the other hand, if your customer requests shipments on a different date from the plan it is a miss even if you could have shipped it according to the forecast plan.